Income Tax Expense (Schedule of Components of Income Tax Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current tax expense:
Federal	$ 17,864	$ 16,286	$ 13,518
State	1,194	866	742
Total current tax expense	19,058	17,152	14,260
Deferred tax expense (benefit):
Federal	2,003	1,820	2,300
State	(183)	27	(33)
Total deferred tax expense	1,820	1,847	2,267
Total income tax expense	$ 20,878	$ 18,999	$ 16,527