Schedule III - Real Estate and Accumulated Depreciation and Amortization - Summary (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Real Estate and Accumulated Depreciation [Line Items]
Total cost basis for federal income tax purposes	$ 3,800,000
Reconciliation of real estate owned:
Balance at the beginning of year	3,090,134	$ 3,936,459	$ 3,533,172
Additions during year	663,742	310,207	676,355
Properties sold and impaired during the year	(496,730)	(1,091,956)	(270,241)
Other reclassifications	63,428	(64,576)	(2,827)
Balance at end of year	3,320,574	3,090,134	3,936,459
Reconciliation of accumulated depreciation and amortization:
Balance at the beginning of year	722,644	890,969	844,931
Depreciation and amortization expense	118,525	136,571	139,493
Accumulated depreciation and amortization of properties sold, impaired and held for sale during year	(177,709)	(290,938)	(93,455)
Other reclassifications	12,136	(13,958)	0
Balance at end of year	$ 675,596	$ 722,644	$ 890,969