Condensed Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning balance at Dec. 31, 2014	$ 418,172	$ 244,318	$ 176,057	$ (2,203)
Beginning balance, shares at Dec. 31, 2014		22,714,964
Net income	32,396		32,396
Other comprehensive income	(95)			(95)
PSU vesting	137	$ 137
RSU vesting	338	338
RSUs released
RSUs released, shares		11,652
Tax benefit from release of RSUs	15	$ 15
Stock option vesting	576	576
Stock options exercised	1,327	$ 1,327
Stock options exercised, shares		68,000
Tax benefit of stock options exercised	24	$ 24
Reversal of tax benefit from Exercise of stock options	(96)	(96)
Repurchase of common stock	(721)	$ (327)	(394)
Repurchase of common stock, shares		(30,321)
Dividends paid	(8,728)		(8,728)
Ending balance at Sep. 30, 2015	443,345	$ 246,312	199,331	(2,298)
Ending balance, shares at Sep. 30, 2015		22,764,295
Net income	11,422
Ending balance at Dec. 31, 2015	$ 452,116	$ 247,587	206,307	(1,778)
Ending balance, shares at Dec. 31, 2015	22,775,173	22,775,173
Net income	$ 32,278		32,278
Other comprehensive income	6,731			6,731
PSU vesting	183	$ 183
RSU vesting	440	440
RSUs released
RSUs released, shares		20,529
Tax benefit from release of RSUs	1	$ 1
Stock option vesting	455	455
Stock options exercised	$ 2,908	$ 2,908
Stock options exercised, shares	132,700	132,700
Tax effect of stock option exercise	$ (183)	$ (183)
Repurchase of common stock	(2,774)	$ (1,101)	(1,673)
Repurchase of common stock, shares		(101,125)
Dividends paid	(10,265)		(10,265)
Ending balance at Sep. 30, 2016	$ 481,890	$ 250,290	$ 226,647	$ 4,953
Ending balance, shares at Sep. 30, 2016	22,827,277	22,827,277