Income Taxes (Schedule of Allocation of Federal and State Income Taxes) (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current
Federal													$ 5,584	$ 3,675	$ 3,255
State													1,686	1,296	1,128
Current income tax expense (benefit), total													7,270	4,971	4,383
Deferred
Federal													1,894	(460)	(643)
State													(7)	(95)	(107)
Deferred income tax expense (benefit), total													1,887	(555)	(750)
Income tax expense (benefit), total	$ 4,456	$ 1,717	$ 1,536	$ 1,448	$ 1,356	$ 1,014	$ 1,078	$ 968	$ 811	$ 735	$ 1,004	$ 1,083	$ 9,157	$ 4,416	$ 3,633