Income Taxes (Components of Income Taxes) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current:
U.S. Federal	$ 29,185	$ 40,542	$ 8,809
State	7,407	13,886	2,416
Current Total	36,592	54,428	11,225
Deferred:
U.S. Federal	10,076	(9,943)	16,484
State	2,495	(3,252)	5,456
Deferred Total	12,571	(13,195)	21,940
Income tax expense	$ 49,163	$ 41,233	$ 33,165