Condensed Consolidating Financial Statements (Condensed Consolidating Statement of Operations) (Details) (USD $)
In Thousands, unless otherwise specified
 3 Months Ended 12 Months Ended
Dec. 31, 2014
Sep. 30, 2014
Jun. 30, 2014
Mar. 31, 2014
Dec. 31, 2013
Sep. 30, 2013
Jun. 30, 2013
Mar. 31, 2013
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Operating revenues $ 854,231 $ 926,727 $ 951,981 $ 955,781 $ 1,063,767 $ 1,085,633 $ 1,245,451 $ 1,316,716 $ 3,688,720 $ 4,711,567 $ 5,693,235
Cost of revenues (exclusive of depreciation and amortization included below)                 2,282,326 2,276,929 2,302,009
Selling, general and administrative                 1,699,058 1,941,773 2,261,922
Restructuring, Settlement and Impairment Provisions                 220,742 168,543 30,401
Gain (Loss) on Sale of Assets and Asset Impairment Charges                 (74,631) 0 0
Management fee and other                 0 0 0
Depreciation and amortization                 672,705 692,927 605,161
Total operating expenses                 4,800,200 5,080,172 5,199,493
Operating income (335,737) (212,900) (350,553) (212,290) (155,666) (127,889) (40,653) (44,397) (1,111,480) (368,605) 493,742
Interest expense, net                 (449,345) (526,530) (359,795)
Intercompany interest expense                 0 0 0
Interest income                 66,425 43,327 33,785
Intercompany interest income                 0 0 0
Foreign currency transaction losses, net                 (130,499) (123,369) (63,330)
Equity in income of affiliates                 0 0 0
Other income (expense), net                 (6,721) (12,859) (28,097)
Total other expense                 (520,140) (619,431) (417,437)
(Loss) income from continuing operations before reorganization items and income tax provision                 (1,631,620) (988,036) 76,305
Reorganization Items                 (71,601) 0 0
Income tax provision (Note 13)                 (74,091) (446,052) (158,144)
Net loss from continuing operations (507,306) (456,753) (474,983) (338,270) (705,460) (259,507) (316,018) (153,103) (1,777,312) (1,434,088) (81,839)
Loss from discontinued operations, net of income taxes (Note 5) (7,555) 13,306 (148,329) (37,808) (40,343) (40,434) (80,334) (54,400) (180,386) (215,511) (683,410)
Net loss                 (1,957,698) (1,649,599) (765,249)
Comprehensive loss, net of income taxes                      
Foreign currency translation adjustment                 (340,847) (334,893) (97,589)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax                 (33,885) 0 0
Other                 (544) 2,257 (1,802)
Other comprehensive loss                 (375,276) (332,636) (99,391)
Net (loss) income                 (1,957,698) (1,649,599) (765,249)
Total comprehensive loss                 (2,332,974) (1,982,235) (864,640)
NII Holdings Inc. (Parent) [Member]                      
Operating revenues                 0 0 0
Cost of revenues (exclusive of depreciation and amortization included below)                 0 0 0
Selling, general and administrative                 2,145 3,136 3,180
Restructuring, Settlement and Impairment Provisions                 0 0 0
Gain (Loss) on Sale of Assets and Asset Impairment Charges                 0    
Management fee and other                 0 0 0
Depreciation and amortization                 0 0 0
Total operating expenses                 2,145 3,136 3,180
Operating income                 (2,145) (3,136) (3,180)
Interest expense, net                 (570) (562) (23,646)
Intercompany interest expense                 (165,324) (234,799) (215,501)
Interest income                 280 913 15,292
Intercompany interest income                 411 1,340 1
Foreign currency transaction losses, net                 0 0 0
Equity in income of affiliates                 (1,805,438) (1,473,856) (639,902)
Other income (expense), net                 8,212 36,017 86,324
Total other expense                 (1,962,429) (1,670,947) (777,432)
(Loss) income from continuing operations before reorganization items and income tax provision                 (1,964,574) (1,674,083) (780,612)
Reorganization Items                 (291) 0 0
Income tax provision (Note 13)                 7,167 24,484 15,363
Net loss from continuing operations                 (1,957,698) (1,649,599) (765,249)
Loss from discontinued operations, net of income taxes (Note 5)                 0 0 0
Net loss                 (1,957,698) (1,649,599) (765,249)
Comprehensive loss, net of income taxes                      
Foreign currency translation adjustment                 (340,847) (334,893) (97,589)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax                 (33,885) 0 0
Other                 (544) 2,257 (1,802)
Other comprehensive loss                 (375,276) (332,636) (99,391)
Net (loss) income                 (1,957,698) (1,649,599) (765,249)
Total comprehensive loss                 (2,332,974) (1,982,235) (864,640)
NII Capital Corp. (Issuer) [Member]                      
Operating revenues                 0 0 0
Cost of revenues (exclusive of depreciation and amortization included below)                 0 0 0
Selling, general and administrative                 2,567 0 2
Restructuring, Settlement and Impairment Provisions                 0 0 0
Gain (Loss) on Sale of Assets and Asset Impairment Charges                 0    
Management fee and other                 0 0 0
Depreciation and amortization                 0 0 0
Total operating expenses                 2,567 0 2
Operating income                 (2,567) 0 (2)
Interest expense, net                 (171,646) (240,132) (229,652)
Intercompany interest expense                 0 0 0
Interest income                 1 0 24,181
Intercompany interest income                 200,467 284,709 261,352
Foreign currency transaction losses, net                 0 0 0
Equity in income of affiliates                 (1,593,607) (1,274,274) (443,294)
Other income (expense), net                 0 0 0
Total other expense                 (1,564,785) (1,229,697) (387,413)
(Loss) income from continuing operations before reorganization items and income tax provision                 (1,567,352) (1,229,697) (387,415)
Reorganization Items                 (45,652)    
Income tax provision (Note 13)                 6,747 (16,548) (19,731)
Net loss from continuing operations                 (1,606,257) (1,246,245) (407,146)
Loss from discontinued operations, net of income taxes (Note 5)                 0 0 0
Net loss                 (1,606,257) (1,246,245) (407,146)
Comprehensive loss, net of income taxes                      
Foreign currency translation adjustment                 (342,432) (335,183) (96,593)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax                 (33,885)    
Other                 (544) 2,257 (1,802)
Other comprehensive loss                 (376,861) (332,926) (98,395)
Net (loss) income                 (1,606,257) (1,246,245) (407,146)
Total comprehensive loss                 (1,983,118) (1,579,171) (505,541)
Guarantor Subsidiaries [Member]                      
Operating revenues                 2,143 3,114 3,071
Cost of revenues (exclusive of depreciation and amortization included below)                 0 0 73
Selling, general and administrative                 140,119 167,180 309,680
Restructuring, Settlement and Impairment Provisions                 63,393 97,063 0
Gain (Loss) on Sale of Assets and Asset Impairment Charges                 0    
Management fee and other                 (48,852) (75,116) (126,971)
Depreciation and amortization                 19,309 28,055 36,079
Total operating expenses                 173,969 217,182 218,861
Operating income                 (171,826) (214,068) (215,790)
Interest expense, net                 (543) (1,379) (2,072)
Intercompany interest expense                 (50) (59) 0
Interest income                 9 9 801
Intercompany interest income                 1,317 549 186
Foreign currency transaction losses, net                 0 0 0
Equity in income of affiliates                 (1,589,367) (1,269,438) (434,443)
Other income (expense), net                 (2) 612 101
Total other expense                 (1,588,636) (1,269,706) (435,427)
(Loss) income from continuing operations before reorganization items and income tax provision                 (1,760,462) (1,483,774) (651,217)
Reorganization Items                 (13,932)    
Income tax provision (Note 13)                 (18,678) (18,111) (24,833)
Net loss from continuing operations                 (1,793,072) (1,501,885) (676,050)
Loss from discontinued operations, net of income taxes (Note 5)                 0 0 0
Net loss                 (1,793,072) (1,501,885) (676,050)
Comprehensive loss, net of income taxes                      
Foreign currency translation adjustment                 (342,432) (335,183) (96,593)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax                 (33,885)    
Other                 (544) 2,257 (1,802)
Other comprehensive loss                 (376,861) (332,926) (98,395)
Net (loss) income                 (1,793,072) (1,501,885) (676,050)
Total comprehensive loss                 (2,169,933) (1,834,811) (774,445)
Prior Group of Non-Guarantor Subsidiaries [Member]                      
Operating revenues                 3,688,369 4,711,525 5,694,718
Cost of revenues (exclusive of depreciation and amortization included below)                 2,282,326 2,276,929 2,303,419
Selling, general and administrative                 1,561,410 1,779,719 1,962,033
Restructuring, Settlement and Impairment Provisions                 157,349 71,480 30,401
Gain (Loss) on Sale of Assets and Asset Impairment Charges                 (74,631)    
Management fee and other                 51,672 106,264 225,202
Depreciation and amortization                 653,396 664,872 569,082
Total operating expenses                 4,631,522 4,899,264 5,090,137
Operating income                 (943,153) (187,739) 604,581
Interest expense, net                 (478,784) (284,457) (104,425)
Intercompany interest expense                 165,374 (51,740) (84,202)
Interest income                 66,135 42,405 (6,489)
Intercompany interest income                 3 0 38,164
Foreign currency transaction losses, net                 (130,499) (123,369) (63,330)
Equity in income of affiliates                 0 0 0
Other income (expense), net                 (7,706) (13,150) (6,389)
Total other expense                 (385,477) (430,311) (226,671)
(Loss) income from continuing operations before reorganization items and income tax provision                 (1,328,630) (618,050) 377,910
Reorganization Items                 (11,726)    
Income tax provision (Note 13)                 (69,327) (435,877) (128,943)
Net loss from continuing operations                 (1,409,683) (1,053,927) 248,967
Loss from discontinued operations, net of income taxes (Note 5)                 (179,686) (215,511) (683,410)
Net loss                 (1,589,369) (1,269,438) (434,443)
Comprehensive loss, net of income taxes                      
Foreign currency translation adjustment                 (342,432) (335,183) (96,593)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax                 (33,885)    
Other                 (544) 2,257 (1,802)
Other comprehensive loss                 (376,861) (332,926) (98,395)
Net (loss) income                 (1,589,369) (1,269,438) (434,443)
Total comprehensive loss                 (1,966,230) (1,602,364) (532,838)
Prior Consolidating Adjustments [Member]                      
Operating revenues                 (1,792) (3,072) (4,554)
Cost of revenues (exclusive of depreciation and amortization included below)                 0 0 (1,483)
Selling, general and administrative                 (7,183) (8,262) (12,973)
Restructuring, Settlement and Impairment Provisions                 0 0 0
Gain (Loss) on Sale of Assets and Asset Impairment Charges                 0    
Management fee and other                 (2,820) (31,148) (98,231)
Depreciation and amortization                 0 0 0
Total operating expenses                 (10,003) (39,410) (112,687)
Operating income                 8,211 36,338 108,133
Interest expense, net                 202,198 0 0
Intercompany interest expense                 0 286,598 299,703
Interest income                 0 0 0
Intercompany interest income                 (202,198) (286,598) (299,703)
Foreign currency transaction losses, net                 0 0 0
Equity in income of affiliates                 4,988,412 4,017,568 1,517,639
Other income (expense), net                 (7,225) (36,338) (108,133)
Total other expense                 4,981,187 3,981,230 1,409,506
(Loss) income from continuing operations before reorganization items and income tax provision                 4,989,398 4,017,568 1,517,639
Reorganization Items                 0    
Income tax provision (Note 13)                 0 0 0
Net loss from continuing operations                 4,989,398 4,017,568 1,517,639
Loss from discontinued operations, net of income taxes (Note 5)                 (700) 0 0
Net loss                 4,988,698 4,017,568 1,517,639
Comprehensive loss, net of income taxes                      
Foreign currency translation adjustment                 1,027,296 1,005,549 289,779
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax                 101,655    
Other                 1,632 (6,771) 5,406
Other comprehensive loss                 1,130,583 998,778 295,185
Net (loss) income                 4,988,698 4,017,568 1,517,639
Total comprehensive loss                 $ 6,119,281 $ 5,016,346 $ 1,812,824