SCHEDULE III REAL ESTATE AND ACCUMULATED DEPRECIATION - Rollforward (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Carrying cost:      
Balance at beginning of period $ 2,706,625 $ 2,692,498 $ 2,672,101
Additions during period:      
Acquisitions 553,981 13,194 11,791
Capital expenditures 38,592 16,426 11,550
Other 59,688 0 0
Deletions during period:      
Sales and/or transfers to assets held for sale (53,790) (15,493) (2,944)
Balance at end of period 3,305,096 2,706,625 2,692,498
Accumulated depreciation:      
Balance at beginning of period 567,353 483,017 396,401
Additions during period:      
Depreciation and impairment expense 128,138 95,058 89,193
Deletions during period:      
Sales and/or transfers to assets held for sale (30,692) (10,722) (2,577)
Other (5,711) 0 0
Balance at end of period $ 659,088 $ 567,353 $ 483,017