Condensed Consolidating Financial Statements (Condensed Consolidating Statement of Cash Flows) (Details) (USD $)
In Thousands, unless otherwise specified
 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Cash flows from operating activities:      
Net loss $ (1,957,698) $ (1,649,599) $ (765,249)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities 1,391,565 1,621,281 1,328,968
Total operating cash (used in) provided by continuing operations (566,133) (28,318) 563,719
Total operating cash used in discontinued operations (62,583) (164,133) (210,536)
Net cash (used in) provided by operating activities (628,716) (192,451) 353,183
Cash flows from investing activities:      
Capital expenditures (612,161) (620,895) (953,882)
Purchases of licenses   (53,066) (100,185)
Purchase of investments (1,637,913) (2,360,529) (1,678,918)
Proceeds from sales of investments 2,092,459 1,942,886 1,813,783
Increase (Decrease) in Restricted Cash 137,827 39,436 4,087
(Payments) proceeds related to 2013 sale of towers, net (39,618) 721,404 0
Transfers to restricted cash   (41,709) (11,969)
Transfers from restricted cash   2,273 7,882
Proceeds from 2013 sale of towers, net   721,404 0
Investment in subsidiaries 0 0 0
Other, net (38,098) 207 1,018
Total investing cash used in continuing operations (333,540) (409,429) (922,271)
Total investing cash (used in) provided by discontinued operations (13,998) 231,817 (132,889)
Net cash used in investing activities (347,538) (177,612) (1,055,160)
Net Cash Provided by (Used in) Financing Activities [Abstract]      
Proceeds from issuance of senior notes 0 1,600,000 0
Borrowings under line of credit   1,600,000 212,770
Borrowings under equipment financing 14,590 145,077 233,776
Repayments under syndicated loan facilities (48,920) (323,919) (97,403)
Repayments of import financing   (37,422) (175,923)
Repayments Under Tower Financing and Other Borrowings 39,243 63,495  
Payment of line of credit (54,067)    
Intercompany dividends   0 0
Capital contributions 0 0 0
Proceeds From Intercompany Long Term Loan     0
Repayments of Convertible Debt 0 0 (212,782)
Payment of line of credit   (362,735)  
Other, net (632) (27,950) (124,723)
Total financing cash (used in) provided by continuing operations (128,272) 929,556 (164,285)
Total financing cash used in discontinued operations 0 (152,965) (74,010)
Net cash (used in) provided by financing activities (128,272) 776,591 (238,295)
Effect of exchange rate changes on cash and cash equivalents (55,657) (56,236) 844
Change in cash and cash equivalents related to discontinued operations 3,448 15,090 22,226
Net (decrease) increase in cash and cash equivalents (1,156,735) 365,382 (917,202)
Cash and cash equivalents, beginning of year 1,730,335 1,364,953 2,282,155
Cash and cash equivalents, end of year 573,600 1,730,335 1,364,953
NII Holdings Inc. (Parent) [Member]      
Cash flows from operating activities:      
Net loss (1,957,698) (1,649,599) (765,249)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities 1,861,773 1,477,932 768,542
Total operating cash (used in) provided by continuing operations (95,925) (171,667) 3,293
Total operating cash used in discontinued operations 0 0 0
Net cash (used in) provided by operating activities (95,925) (171,667) 3,293
Cash flows from investing activities:      
Capital expenditures 0 0 0
Purchases of licenses   0 0
Purchase of investments 0 0 0
Proceeds from sales of investments 0 0 224,330
Increase (Decrease) in Restricted Cash (25,300) 15,050 0
Transfers to restricted cash   (15,050) 0
Transfers from restricted cash   0 0
Proceeds from 2013 sale of towers, net   0 0
Investment in subsidiaries (180,712) (191,526) (318,949)
Other, net 1,856 545 0
Total investing cash used in continuing operations (153,556) (206,031) (94,619)
Total investing cash (used in) provided by discontinued operations 0 0 0
Net cash used in investing activities (153,556) (206,031) (94,619)
Net Cash Provided by (Used in) Financing Activities [Abstract]      
Borrowings under line of credit   0 0
Borrowings under equipment financing 0 0 0
Repayments under syndicated loan facilities 0 0 0
Repayments of import financing   0 0
Repayments Under Tower Financing and Other Borrowings 0 0  
Payment of line of credit 0    
Intercompany dividends   0 0
Capital contributions 0 0 0
Proceeds From Intercompany Long Term Loan     0
Repayments of Convertible Debt 0 0 (212,782)
Payment of line of credit   0  
Other, net (86) (1,010) (3,228)
Total financing cash (used in) provided by continuing operations   (1,010) (216,010)
Total financing cash used in discontinued operations   0 0
Net cash (used in) provided by financing activities (86) (1,010) (216,010)
Effect of exchange rate changes on cash and cash equivalents 0 0 0
Change in cash and cash equivalents related to discontinued operations 0 0 0
Net (decrease) increase in cash and cash equivalents (249,567) (378,708) (307,336)
Cash and cash equivalents, beginning of year 356,314 735,022 1,042,358
Cash and cash equivalents, end of year 106,747 356,314 735,022
NII Holdings,Inc. (Parent and Guarantor) [Member]      
Cash flows from investing activities:      
Other, net 1,856    
NII Capital Corp. (Issuer) [Member]      
Cash flows from operating activities:      
Net loss (1,606,257) (1,246,245) (407,146)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities 1,631,873 1,298,129 567,599
Total operating cash (used in) provided by continuing operations 25,616 51,884 160,453
Total operating cash used in discontinued operations 0 0 0
Net cash (used in) provided by operating activities 25,616 51,884 160,453
Cash flows from investing activities:      
Capital expenditures 0 0 0
Purchases of licenses   0 0
Purchase of investments 0 0 0
Proceeds from sales of investments 0 0 0
Increase (Decrease) in Restricted Cash 0    
Transfers to restricted cash   0 0
Transfers from restricted cash   0 0
Proceeds from 2013 sale of towers, net   0 0
Investment in subsidiaries (446) (1,974) (9,445)
Other, net 0 0 0
Total investing cash used in continuing operations (446) (1,974) (9,445)
Total investing cash (used in) provided by discontinued operations 0 0 0
Net cash used in investing activities (446) (1,974) (9,445)
Net Cash Provided by (Used in) Financing Activities [Abstract]      
Borrowings under line of credit   0 0
Borrowings under equipment financing 0 0 0
Repayments under syndicated loan facilities 0 0 0
Repayments of import financing   0 0
Repayments Under Tower Financing and Other Borrowings 0 0  
Payment of line of credit 0    
Intercompany dividends   (49,910) (151,186)
Capital contributions 20 20 0
Proceeds From Intercompany Long Term Loan     0
Repayments of Convertible Debt     0
Payment of line of credit   0  
Other, net (20) (20) (778)
Total financing cash (used in) provided by continuing operations   (49,910) (151,964)
Total financing cash used in discontinued operations   0 0
Net cash (used in) provided by financing activities 0 (49,910) (151,964)
Effect of exchange rate changes on cash and cash equivalents 0 0 0
Change in cash and cash equivalents related to discontinued operations 0 0 0
Net (decrease) increase in cash and cash equivalents 25,170 0 (956)
Cash and cash equivalents, beginning of year 0 [1] 0 956
Cash and cash equivalents, end of year 25,170 [1] 0 [1] 0
Guarantor Subsidiaries [Member]      
Cash flows from operating activities:      
Net loss (1,793,072) (1,501,885) (676,050)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities 1,640,357 1,340,701 564,974
Total operating cash (used in) provided by continuing operations (152,715) (161,184) (111,076)
Total operating cash used in discontinued operations 0 1,440 2,142
Net cash (used in) provided by operating activities (152,715) (159,744) (108,934)
Cash flows from investing activities:      
Capital expenditures (7,012) (14,232) (92,574)
Purchases of licenses   0 0
Purchase of investments 0 0 0
Proceeds from sales of investments 0 0 0
Increase (Decrease) in Restricted Cash 0    
Transfers to restricted cash   0 0
Transfers from restricted cash   0 0
Proceeds from 2013 sale of towers, net   0 0
Investment in subsidiaries 0 (1,260) 0
Other, net 32,390 0 0
Total investing cash used in continuing operations 25,378 (15,492) (92,574)
Total investing cash (used in) provided by discontinued operations 0 0 0
Net cash used in investing activities 25,378 (15,492) (92,574)
Net Cash Provided by (Used in) Financing Activities [Abstract]      
Borrowings under line of credit   0 0
Borrowings under equipment financing 0 0 0
Repayments under syndicated loan facilities (42,414) 0 0
Repayments of import financing   0 0
Repayments Under Tower Financing and Other Borrowings 0 16,608  
Payment of line of credit 0    
Intercompany dividends   0 (100,320)
Capital contributions 180,525 191,506 318,949
Proceeds From Intercompany Long Term Loan     300
Repayments of Convertible Debt     0
Payment of line of credit   0  
Other, net (1,855) (545) (19,368)
Total financing cash (used in) provided by continuing operations   174,353 199,561
Total financing cash used in discontinued operations   0 0
Net cash (used in) provided by financing activities 136,256 174,353 199,561
Effect of exchange rate changes on cash and cash equivalents 0 0 0
Change in cash and cash equivalents related to discontinued operations 0 0 0
Net (decrease) increase in cash and cash equivalents 8,919 (883) (1,947)
Cash and cash equivalents, beginning of year 5,586 [2] 6,469 8,416
Cash and cash equivalents, end of year 14,505 [2] 5,586 [2] 6,469
Prior Group of Non-Guarantor Subsidiaries [Member]      
Cash flows from operating activities:      
Net loss (1,589,369) (1,269,438) (434,443)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities 1,246,260 1,571,997 1,296,998
Total operating cash (used in) provided by continuing operations (343,109) 302,559 862,555
Total operating cash used in discontinued operations (62,583) (165,573) (212,678)
Net cash (used in) provided by operating activities (405,692) 136,986 649,877
Cash flows from investing activities:      
Capital expenditures (605,149) (606,663) (861,308)
Purchases of licenses   (53,066) (100,185)
Purchase of investments (1,637,913) (2,360,529) (1,678,918)
Proceeds from sales of investments 2,092,459 1,942,886 1,589,453
Increase (Decrease) in Restricted Cash 163,127    
Transfers to restricted cash   (26,659) (11,969)
Transfers from restricted cash   2,273 7,882
Proceeds from 2013 sale of towers, net   721,404 (300)
Investment in subsidiaries 0 0 0
Other, net (70,488) 191 1,018
Total investing cash used in continuing operations (384,218) (380,163) (1,054,327)
Total investing cash (used in) provided by discontinued operations (13,998) 231,817 (132,889)
Net cash used in investing activities (398,216) (148,346) (1,187,216)
Net Cash Provided by (Used in) Financing Activities [Abstract]      
Borrowings under line of credit   1,600,000 212,770
Borrowings under equipment financing 14,590 145,077 233,776
Repayments under syndicated loan facilities (6,506) (323,919) (97,403)
Repayments of import financing   (37,422) (175,923)
Repayments Under Tower Financing and Other Borrowings 39,243 46,887  
Payment of line of credit (54,067)    
Intercompany dividends   0 (100,000)
Capital contributions 613 3,234 9,445
Proceeds From Intercompany Long Term Loan     0
Repayments of Convertible Debt     0
Payment of line of credit   (362,735)  
Other, net (527) (26,904) (101,349)
Total financing cash (used in) provided by continuing operations   950,444 (18,684)
Total financing cash used in discontinued operations   (152,965) (74,010)
Net cash (used in) provided by financing activities (85,140) 797,479 (92,694)
Effect of exchange rate changes on cash and cash equivalents (55,657) (56,236) 844
Change in cash and cash equivalents related to discontinued operations 3,448 15,090 22,226
Net (decrease) increase in cash and cash equivalents (941,257) 744,973 (606,963)
Cash and cash equivalents, beginning of year 1,368,435 623,462 1,230,425
Cash and cash equivalents, end of year 427,178 1,368,435 623,462
Prior Consolidating Adjustments [Member]      
Cash flows from operating activities:      
Net loss 4,988,698 4,017,568 1,517,639
Adjustments to reconcile net loss to net cash (used in) provided by operating activities (4,988,698) (4,067,478) (1,869,145)
Total operating cash (used in) provided by continuing operations 0 (49,910) (351,506)
Total operating cash used in discontinued operations 0 0 0
Net cash (used in) provided by operating activities 0 (49,910) (351,506)
Cash flows from investing activities:      
Capital expenditures 0 0 0
Purchases of licenses   0 0
Purchase of investments 0 0 0
Proceeds from sales of investments 0 0 0
Increase (Decrease) in Restricted Cash 0    
Transfers to restricted cash   0 0
Transfers from restricted cash   0 0
Proceeds from 2013 sale of towers, net   0 300
Investment in subsidiaries 181,158 194,760 328,394
Other, net (1,856) (529) 0
Total investing cash used in continuing operations 179,302 194,231 328,694
Total investing cash (used in) provided by discontinued operations 0 0 0
Net cash used in investing activities 179,302 194,231 328,694
Net Cash Provided by (Used in) Financing Activities [Abstract]      
Borrowings under line of credit   0 0
Borrowings under equipment financing 0 0 0
Repayments under syndicated loan facilities 0 0 0
Repayments of import financing   0 0
Repayments Under Tower Financing and Other Borrowings 0 0  
Payment of line of credit 0    
Intercompany dividends   49,910 351,506
Capital contributions (181,158) (194,760) (328,394)
Proceeds From Intercompany Long Term Loan     (300)
Repayments of Convertible Debt     0
Payment of line of credit   0  
Other, net 1,856 529 0
Total financing cash (used in) provided by continuing operations   (144,321) 22,812
Total financing cash used in discontinued operations   0 0
Net cash (used in) provided by financing activities (179,302) (144,321) 22,812
Effect of exchange rate changes on cash and cash equivalents 0 0 0
Change in cash and cash equivalents related to discontinued operations 0 0 0
Net (decrease) increase in cash and cash equivalents 0 0 0
Cash and cash equivalents, beginning of year 0 0 0
Cash and cash equivalents, end of year $ 0 $ 0 $ 0
[1] NII Capital Corp. is the issuer of our 7.625% senior notes due 2021, our 10.0% senior notes due 2016 and our 8.875% senior notes due 2019.
[2] Represents our subsidiaries that have provided guarantees of the obligations of NII Capital Corp. under our 7.625% senior notes due 2021, our 10.0% senior notes due 2016 and our 8.875% notes due 2019.