Schedule III - Real Estate and Accumulated Depreciation (Details) - Reconciliation of Real Estate - Owned Subject to Operating Leases - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]
Balance	$ 3,160,472	$ 3,109,397	$ 2,687,018
Property improvements during the year	37,985	40,300	54,481
Properties acquired during the year	11,601	43,387	374,004
Properties sold during the year	69,056	24,427	0
Assets written off during the year	(9,161)	(8,185)	(6,106)
Balance	$ 3,131,841	$ 3,160,472	$ 3,109,397