Income Taxes Components of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
Federal	$ 106,710	$ 93,538	$ 76,902
State	9,446	8,121	6,567
Foreign	217	265	188
Total Current	116,373	101,924	83,657
Deferred:
Federal	(59,517)	17,057	17,317
State	638	597	1,753
Foreign	(393)	(158)	193
Total Deferred	(59,272)	17,496	19,263
Total	$ 57,101	$ 119,420	$ 102,920