Derivatives (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Stockholders' equity	$ (4,287,839)	$ (4,300,935)	$ (4,319,304)	$ (4,331,682)
Reclassification to interest expense	(1,368)	$ (383)
Interest rate cash flow hedge gain (loss) to be reclassified over next 12 months, net	(2,271)
AOCI, cash flow hedges
Derivative [Line Items]
Stockholders' equity	$ 15,077		$ 16,445