Condensed Consolidated Statements of Changes in Shareholders' Equity (USD $) In Thousands, except Share data	Total	Common Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]
Beginning balance at Dec. 31, 2012	$ 229,359	$ 85,561	$ 141,639	$ 2,159
Beginning balance, shares at Dec. 31, 2012		16,000,838
Net income	22,163		22,163
Other comprehensive loss	(2,027)			(2,027)
Stock option vesting	849	849
Stock option forfeiture	(22)	(22)
Stock options exercised	3,240	3,240
Stock options exercised, shares		248,765
Tax benefit of stock options exercised	356	356
Repurchase of common stock	(3,490)	(930)	(2,560)
Repurchase of common stock, shares		(172,941)
Dividends paid	(4,976)		(4,976)
Ending balance at Sep. 30, 2013	245,452	89,054	156,266	132
Ending balance, shares at Sep. 30, 2013		16,076,662
Beginning balance at Dec. 31, 2013	250,946	89,356	159,733	1,857
Beginning balance, shares at Dec. 31, 2013	16,076,662	16,076,662
Net income	20,458		20,458
Other comprehensive loss	(61)			(61)
Stock option vesting	745	745
RSU vesting	49	49
PSU vesting	16	16
Stock options exercised	2,875	2,875
Stock options exercised, shares	166,020	166,020
Tax benefit of stock options exercised	225	225
Repurchase of common stock	(2,551)	(574)	(1,977)
Repurchase of common stock, shares		(103,268)
Dividends paid	(5,322)		(5,322)
Ending balance at Sep. 30, 2014	$ 267,380	$ 92,692	$ 172,892	$ 1,796
Ending balance, shares at Sep. 30, 2014	16,139,414	16,139,414