SCHEDULE III REAL ESTATE AND ACCUMULATED DEPRECIATION - Analysis of Carrying Amount of Real Estate Properties and Accumulated Depreciation (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Real Estate Properties
Additions		$ 13,900,000	$ 56,300,000	$ 55,000,000.0
Loss on asset impairment	$ (12,100,000)	0	(12,087,000)	(19,714,000)
Balance at the end of the year		662,121,000
Accumulated Depreciation
Balance at the beginning of the year	450,718,000	375,968,000	450,718,000	755,255,000
Additions		22,697,000	39,161,000	71,979,000
Loss on asset impairment			0	0
Properties classified to held for sale				(62,064,000)
Disposals		(195,965,000)	(113,911,000)	(314,452,000)
Balance at the end of the year		202,700,000	375,968,000	450,718,000
Real Estate Properties
Real Estate Properties
Balance at the beginning of the year	$ 1,747,611,000	1,139,642,000	1,747,611,000	2,856,890,000
Additions		13,895,000	58,618,000	55,041,000
Loss on asset impairment			(12,032,000)	(6,711,000)
Properties classified to held for sale				(138,130,000)
Disposals		(491,416,000)	(654,555,000)	(1,019,479,000)
Balance at the end of the year		$ 662,121,000	$ 1,139,642,000	$ 1,747,611,000