Income Taxes (Schedule of Effective Income Tax Rate Reconciliation) (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
Expected income tax expense at federal tax rate													$ 5,728	$ 3,994	$ 3,392
State taxes net of federal benefit													1,096	796	647
Nondeductible expenses													255	37	40
Nontaxable income													(376)	(375)	(398)
Provisional deferred tax adjustment related to reduction in U.S. federal statutory income tax rate													2,740
Other													(286)	(36)	(48)
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
Expected income tax expense at federal tax rate													35.00%	34.00%	34.00%
State taxes net of federal benefit													6.70%	6.78%	6.49%
Nondeductible expenses													1.56%	0.31%	0.40%
Nontaxable income													(2.30%)	(3.19%)	(3.99%)
Provisional deferred tax adjustment related to reduction in U.S. federal statutory income tax rate													16.74%	0.00%	0.00%
Other													(1.75%)	(0.31%)	(0.48%)
Total income tax expense													55.95%	37.59%	36.42%
Parent Company [Member]
Income tax expense (benefit), total													$ (1,583)	$ (1,321)	$ (1,009)