Parent Company Information (Components of Condensed Comprehensive Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other comprehensive income (loss), net of tax:
Derivative instruments	$ 29,102	$ 129	$ 5,703
Other comprehensive (loss) income, net of tax	78,328	94,580	(39,121)
Parent Company [Member]
Condensed Statement of Income Captions [Line Items]
Net income	220,621	382,723	360,418
Other comprehensive income (loss), net of tax:
Derivative instruments	2,622	1,479	1,447
Other comprehensive income (loss) of subsidiaries	75,706	93,101	(40,568)
Other comprehensive (loss) income, net of tax	78,328	94,580	(39,121)
Comprehensive income	$ 298,949	$ 477,303	$ 321,297