Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) of the Company [Roll Forward]
Beginning Balance	$ 6,589,454	$ 7,750,911	$ 7,719,317
Other comprehensive (loss) income before reclassifications	(2,304)	(2,733)	18,211
Amounts reclassified from accumulated other comprehensive income	(1,192)	(800)	12,675
Ending Balance	5,947,855	6,589,454	7,750,911
Deferred net losses from terminated hedges	1,300	3,200
Net unrealized (loss) gain on derivative instruments
Accumulated Other Comprehensive Income (Loss) of the Company [Roll Forward]
Beginning Balance	12,542	12,596	(10,160)
Other comprehensive (loss) income before reclassifications	(2,252)	(1,618)	13,534
Amounts reclassified from accumulated other comprehensive income	(574)	1,564	9,222
Ending Balance	9,716	12,542	12,596
Net unrealized gain on marketable securities
Accumulated Other Comprehensive Income (Loss) of the Company [Roll Forward]
Beginning Balance	1,042	5,520	2,003
Other comprehensive (loss) income before reclassifications	51	(1,348)	3,517
Amounts reclassified from accumulated other comprehensive income	0	(3,130)	0
Ending Balance	1,093	1,042	5,520
Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) of the Company [Roll Forward]
Beginning Balance	18,604	22,137	(8,749)
Ending Balance	15,108	18,604	22,137
Joint venture | Net unrealized (loss) gain on derivative instruments
Accumulated Other Comprehensive Income (Loss) of the Company [Roll Forward]
Beginning Balance	5,020	4,021	(592)
Other comprehensive (loss) income before reclassifications	(103)	233	1,160
Amounts reclassified from accumulated other comprehensive income	(618)	766	3,453
Ending Balance	$ 4,299	$ 5,020	$ 4,021