Income Taxes (Schedule of Components of Income Tax Expense (Benefit)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current expense:
Federal	$ 999	$ 158	$ 0
State	1,733	2,076	819
Total current expense	2,732	2,234	819
Deferred expense:
Federal	36,569	13,146	8,412
State	(270)	1	(60)
Total deferred expense	36,299	13,147	8,352
Total income tax provision	$ 39,031	$ 15,381	$ 9,171