Income Taxes (Schedule of Components of Income Tax Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current expense:
Federal	$ 86,977	$ 81,459	$ 80,360
State	17,733	12,657	13,663
Foreign	23,845	24,608	25,001
Current expense (benefit)	128,555	118,724	119,024
Deferred expense (benefit):
Federal	(2,979)	(2,216)	34,636
State	(405)	(98)	3,627
Foreign	26,543	(36,602)	(4,896)
Deferred expense (benefit)	23,159	(38,916)	33,367
Tax expense (benefit) relating to uncertain tax positions, including accrued interest	(6,323)	(1,338)	3,915
Income tax expense	$ 145,391	$ 78,470	$ 156,306