Land, Buildings and Improvements and Assets Held for Sale - Operating Lease Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Operating Lease, Lease Income [Abstract]
Lease income — fixed	$ 249,356	$ 229,155	$ 725,321	$ 666,330
Lease income – variable	26,871	24,304	74,424	67,917
Total operating lease income	$ 276,227	$ 253,459	$ 799,745	$ 734,247