SCHEDULE III - REAL ESTATE AND ACCUMULATED DEPRECIATION - Property Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Investments in Real Estate
Balance, beginning of period	$ 1,344,636	$ 1,228,780	$ 2,021,494
Additions:
Improvements	18,388	14,906	26,078
Property acquisitions	0	128,928	18,770
Deductions:
Assets held for sale	0	(24,832)	0
Asset sales	(659,849)	0	(815,357)
Impairment	(69,000)	0	(13,100)
Retirements	(4,913)	(3,146)	(9,105)
Balance, end of period	629,262	1,344,636	1,228,780
Accumulated Depreciation
Balance, beginning of period	(303,699)	(271,055)	(414,552)
Additions: depreciation	(22,209)	(43,499)	(49,427)
Assets held for sale	0	7,709	0
Asset sales	200,440	0	183,819
Retirements	4,913	3,146	9,105
Balance, end of period	$ (120,555)	$ (303,699)	$ (271,055)