Revenue Recognition (Components of Lease Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenue from Contract with Customer [Abstract]
Fixed billings	$ 305,963	$ 322,342	$ 615,823	$ 676,656
Variable billings	30,123	25,262	61,772	70,483
Total contractual operating lease billings	336,086	347,604	677,595	747,139
Adjustment for straight-line rents and amortization of acquired below-market leases, net	(3,573)	(1,701)	(9,354)	(8,974)
Less: write-off of straight-line rent and tenant receivables deemed uncollectible	(1,569)	(37,587)	(5,239)	(38,631)
Lease revenues	$ 330,944	$ 308,316	$ 663,002	$ 699,534