Leases - Rental Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Leases [Abstract]
Cash rent	$ 277,324	$ 279,662	$ 559,899	$ 560,550
Straight-line rent	8,043	11,422	15,455	22,387
Lease intangible amortization	(611)	(688)	(1,342)	(2,175)
Sub-lease	5,282	4,080	10,771	8,009
Total fixed	290,038	294,476	584,783	588,771
Variable	21,794	20,943	43,675	41,457
Income from direct financing leases	211	245	428	510
Total rental revenue	$ 312,043	$ 315,664	$ 628,886	$ 630,738