Accounting for the Impairment or Disposal of Long-Lived Assets (Details) (USD $)
In Thousands, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]    
Gain on property dispositions $ 0 $ 46,115
Net income 0 47,848
Discontinued Operations [Member]    
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]    
Revenues 0 4,748
Operating expenses 0 (2,495)
Interest and other income 0 37
Interest expense 0 (557)
Depreciation and amortization 0 0
Income before gain on property dispositions 0 1,733
Gain on property dispositions 0 46,115
Net income $ 0 $ 47,848