Net Income per Share - Reconciliation of Calculation of Basic and Diluted Income Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Earnings Per Share [Abstract]
Net income	$ 5,397	$ 3,444	$ 10,627	$ 6,636
Weighted average common shares outstanding - Basic (in shares)	10,717	10,546	10,698	10,528
Plus: Potential dilutive common stock equivalents (in shares)	198	189	199	192
Weighted average common shares outstanding - Diluted (in shares)	10,915	10,735	10,897	10,720
Net income per common share - Basic (in dollars per share)	$ 0.50	$ 0.33	$ 0.99	$ 0.63
Net income per common share - Diluted (in dollars per share)	$ 0.49	$ 0.32	$ 0.98	$ 0.62
Stock options and common stock excluded from the income per share calculation as their effect would have been anti-dilutive (in shares)	112	77	99	66