Consolidated Statement of Changes in Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock	Capital Surplus	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Total
BALANCE-beginning of period at Dec. 31, 2014	$ 262	$ 252,421	$ 34,660	$ 1,062		$ 288,405
BALANCE-beginning of period (in shares) at Dec. 31, 2014	26,176
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income			8,787			8,787
Net change in unrealized gains and losses on available-for-sale securities, net of taxes and reclassification adjustment				111		111
Issuance of common stock in connection with the exercise of stock options	$ 1	887				888
Issuance of common stock in connection with the exercise of stock options (in shares)	94
Stock-based compensation expense		461				461
BALANCE-end of period at Jun. 30, 2015	$ 263	253,769	43,447	1,173		298,652
BALANCE-end of period (in shares) at Jun. 30, 2015	26,270
BALANCE-beginning of period at Dec. 31, 2015	$ 368	378,518	50,099	417		429,402
BALANCE-beginning of period (in shares) at Dec. 31, 2015	36,788
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income			5,470			5,470
Net change in unrealized gains and losses on available-for-sale securities, net of taxes and reclassification adjustment				631		631
Issuance of common stock in connection with the exercise of stock options		71				71
Purchase of treasury stock						(1,253)
Purchase of treasury stock (in shares)					(1,253)
Stock-based compensation expense		620				620
BALANCE-end of period at Jun. 30, 2016	$ 368	$ 379,209	$ 55,569	$ 1,048	$ (1,253)	$ 434,941
BALANCE-end of period (in shares) at Jun. 30, 2016	36,788