Derivatives (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Stockholders' equity	$ (4,270,878)	$ (4,310,800)	$ (4,270,878)	$ (4,310,800)	$ (4,287,839)	$ (4,319,304)	$ (4,300,935)	$ (4,331,682)
Gain (loss) reclassification to interest expense	(561)	$ (638)	(1,929)	$ (1,021)
Interest rate cash flow hedge gain (loss) to be reclassified over next 12 months, net	(2,295)		(2,295)
AOCI, cash flow hedges
Derivative [Line Items]
Stockholders' equity	$ 14,516		$ 14,516			$ 16,445