SCHEDULE III - REAL ESTATE AND ACCUMULATED DEPRECIATION - Property Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Investments in Real Estate
Balance, beginning of period	$ 629,262	$ 1,344,636	$ 1,228,780
Additions:
Improvements	9,335	18,388	14,906
Property acquisitions	5,709	0	128,928
Deductions:
Assets held for sale	0	0	(24,832)
Asset sales	0	(659,849)	0
Impairment	0	(69,000)	0
Retirements	(7,101)	(4,913)	(3,146)
Balance, end of period	637,205	629,262	1,344,636
Accumulated Depreciation
Balance, beginning of period	(120,555)	(303,699)	(271,055)
Additions: depreciation	(17,711)	(22,209)	(43,499)
Assets held for sale	0	0	7,709
Asset sales	0	200,440	0
Retirements	7,101	4,913	3,146
Balance, end of period	$ (131,165)	$ (120,555)	$ (303,699)