Restatement - Statement of Operations (Details) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Revenues:    
Rentals $ 154,518 $ 137,479
Interest income on loans receivable 1,722 1,837
Earned income from direct financing leases 795 846
Tenant reimbursement income 4,631 3,319
Interest income and other 621 491
Total revenues 162,287 143,972
Expenses:    
General and administrative 12,600 11,067
Property costs 7,407 5,282
Real estate acquisition costs 1,093 1,281
Interest 57,914 54,399
Depreciation and amortization 66,296 60,549
Impairments 2,200 1,911
Total expenses 147,510 134,489
Income from continuing operations before other expense and income tax expense 14,777 9,483
Other expense:    
Loss on debt extinguishment (1,230) 0
Total other expense (1,230) 0
Income from continuing operations before income tax expense 13,547 9,483
Income tax expense (362) (217)
Income from continuing operations 13,185 9,266
Discontinued operations:    
Income from discontinued operations 227 3,054
Loss on dispositions of assets 0 (7)
Income from discontinued operations 227 3,047
Income before gain on dispositions of assets 13,412 12,313
Gain on dispositions of assets 9,151 1,535
Net income $ 22,563 $ 13,848
Net income per share of common stock—basic:    
Continuing operations (in USD per share) $ 0.05 $ 0.03
Discontinued operations (in USD per share) 0.00 0.01
Net income per share attributable to common stockholders—basic (in USD per share) 0.05 0.04
Net income per share of common stock—diluted:    
Continuing operations (in USD per share) 0.05 0.03
Discontinued operations (in USD per share) 0.00 0.01
Net income per share attributable to common stockholders—diluted (in USD per share) $ 0.05 $ 0.04
Weighted average common shares outstanding:    
Basic (in shares) 411,017,895 368,684,942
Diluted (in shares) 411,622,434 369,387,638
As Previously Reported    
Revenues:    
Rentals $ 154,518 $ 137,479
Interest income on loans receivable 1,722 1,837
Earned income from direct financing leases 795 846
Tenant reimbursement income 4,631 3,319
Interest income and other 621 491
Total revenues 162,287 143,972
Expenses:    
General and administrative 12,600 11,067
Property costs 7,407 5,282
Real estate acquisition costs 1,093 1,281
Interest 57,914 54,399
Depreciation and amortization 66,296 60,549
Impairments 1,624 1,707
Total expenses 146,934 134,285
Income from continuing operations before other expense and income tax expense 15,353  
Other expense:    
Loss on debt extinguishment (1,230)  
Total other expense (1,230)  
Income from continuing operations before income tax expense 14,123 9,687
Income tax expense (362) (217)
Income from continuing operations 13,761 9,470
Discontinued operations:    
Income from discontinued operations   3,054
Loss on dispositions of assets   (7)
Income from discontinued operations 227 3,047
Income before gain on dispositions of assets 13,988 12,517
Gain on dispositions of assets 11,336 1,722
Net income $ 25,324 $ 14,239
Net income per share of common stock—basic:    
Continuing operations (in USD per share) $ 0.06 $ 0.03
Discontinued operations (in USD per share) 0.00 0.01
Net income per share attributable to common stockholders—basic (in USD per share) 0.06 0.04
Net income per share of common stock—diluted:    
Continuing operations (in USD per share) 0.06 0.03
Discontinued operations (in USD per share) 0.00 0.01
Net income per share attributable to common stockholders—diluted (in USD per share) $ 0.06 $ 0.04
Weighted average common shares outstanding:    
Basic (in shares) 411,017,895 368,684,942
Diluted (in shares) 411,622,434 369,387,638
Correction of Allocation of Goodwill to the Disposal of Real Estate Assets | Restatement Adjustments    
Revenues:    
Rentals $ 0  
Interest income on loans receivable 0  
Earned income from direct financing leases 0  
Tenant reimbursement income 0  
Interest income and other 0  
Total revenues 0 $ 0
Expenses:    
General and administrative 0  
Property costs 0  
Real estate acquisition costs 0  
Interest 0  
Depreciation and amortization 0  
Impairments 576 204
Total expenses 576 204
Income from continuing operations before other expense and income tax expense (576)  
Other expense:    
Loss on debt extinguishment 0  
Total other expense 0  
Income from continuing operations before income tax expense (576) (204)
Income tax expense 0  
Income from continuing operations (576) (204)
Discontinued operations:    
Income from discontinued operations 0 0
Income before gain on dispositions of assets (576) (204)
Gain on dispositions of assets (2,185) (187)
Net income $ (2,761) $ (391)
Net income per share of common stock—basic:    
Continuing operations (in USD per share) $ (0.01) $ 0.00
Discontinued operations (in USD per share) 0.00 0.00
Net income per share attributable to common stockholders—basic (in USD per share) (0.01) 0.00
Net income per share of common stock—diluted:    
Continuing operations (in USD per share) (0.01) 0.00
Discontinued operations (in USD per share) 0.00 0.00
Net income per share attributable to common stockholders—diluted (in USD per share) $ (0.01) $ 0.00
Weighted average common shares outstanding:    
Basic (in shares) 0 0
Diluted (in shares) 0 0