Leases - Lease Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Interest and Other Income [Abstract]
Fixed income from operating leases	$ 255,447	$ 246,148	$ 730,277	$ 772,388
Variable income from operating leases	57,153	57,706	177,742	166,058
Interest income from direct financing leases	$ 9,590	$ 13,573	$ 33,304	$ 40,329