Income Taxes (Income Tax Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Abstract]
Current federal	$ 38,859	$ 43,777	$ 17,378
Current state	4,112	1,689	4,241
Total current provision	42,971	45,466	21,619
Deferred federal	48,653	(6,127)	15,457
Deferred state	1,178	(1,712)	1,228
Total deferred provision	49,831	(7,839)	16,685
Total included in net income	$ 92,802	$ 37,627	$ 38,304