Discontinued Operations - Summary of Net Gains or Losses from Discontinued 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
Property
Dec. 31, 2013
Property
Dec. 31, 2012
Property
Disposal Group, Including Discontinued Operation, Revenue [Abstract]                      
Rent                 $ 1,206 $ 8,304 $ 12,622
Non-cash rent                 (80) 21 80
Other                 2,972 433 9
Total Revenues                 4,098 8,758 12,711
Expenses:                      
General and administrative                 15 9 214
Property costs                 298 1,009 472
Interest                 0 241 644
Depreciation and amortization                 0 3,545 7,116
Impairments                 417 7,134 4,634
Total expenses                 730 11,938 13,080
Gain (loss) from discontinued operations before other income                 3,368 (3,180) (369)
Other income:                      
Gain on debt extinguishment                 0 1,028 0
Other                 0 75 0
Total other income                 0 1,103 0
Income (loss) from discontinued operations                 3,368 (2,077) (369)
Gain (loss) on dispositions of real estate                 488 36,926 (3,349)
Income (loss) from discontinued operations $ (253) $ 691 $ 371 $ 3,047 $ 35,253 $ 1,231 $ (321) $ (1,314) $ 3,856 $ 34,849 $ (3,718)
Number of properties disposed of during period (1)                 6 22 41