Parent Company Information (Components of Condensed Comprehensive Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other comprehensive income (loss), net of tax:
Derivative instruments	$ 129	$ 5,703	$ 4,565
Other comprehensive (loss) income, net of tax	94,580	(39,121)	1,110
Parent Company [Member]
Condensed Statement of Income Captions [Line Items]
Net income	382,723	360,418	255,439
Other comprehensive income (loss), net of tax:
Derivative instruments	1,479	1,447	1,216
Other comprehensive income (loss) of subsidiaries	93,101	(40,568)	(106)
Other comprehensive (loss) income, net of tax	94,580	(39,121)	1,110
Comprehensive income	$ 477,303	$ 321,297	$ 256,549