Income Taxes (Provision For Income Taxes/(Benefit)) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Components Of Income Tax Expense Benefit Continuing Operations [Abstract]
Current taxes: Federal									$ 143,859	$ 123,802	$ 89,971
Current taxes: State									42,705	30,464	36,070
Current taxes: Foreign									(236)	1,684	99
Current taxes: Total									186,328	155,950	126,140
Deferred taxes: Federal									(31,019)	(7,027)	11,932
Deferred taxes: State									(5,803)	4,266	2,267
Deferred taxes: Foreign									(1,818)	(4,037)	55
Deferred Income Tax Expense (Benefit), Total									(38,640)	(6,798)	14,254
Provision for income taxes	$ 46,232	$ 37,866	$ 35,073	$ 28,517	$ 31,925	$ 40,632	$ 38,225	$ 38,370	$ 147,688	$ 149,152	$ 140,394