Income Taxes (Income Tax Expense (Benefit)) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current income taxes:
Federal									$ 55,664	$ 44,266	$ 54,977
State									18,270	18,349	12,852
Foreign									5,913	(872)	1,243
Total current income taxes									79,847	61,743	69,072
Deferred income taxes:
Federal									33,345	40,500	51,668
State									13,099	11,705	10,403
Foreign									(1,887)	3,019	1,172
Total deferred income taxes									44,557	55,224	63,243
Total income tax expense	$ 30,718	$ 35,480	$ 28,707	$ 29,499	$ 28,005	$ 30,866	$ 32,011	$ 26,085	$ 124,404	$ 116,967	$ 132,315