Income Taxes (Schedule of Income Tax Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current:
Federal	$ 7,305	$ (15,203)	$ 5,920
State	877	1,153	887
Deferred:
Federal	3,325	24,686	3,018
State	307	(6)	191
Investment Tax Credits	(79)	(79)	(79)
Total Income Tax Expense	$ 11,735	$ 10,551	$ 9,937