Consolidated Statements of Changes in Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Common Stock [Member]	Warrant [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Total
Balance (in shares) at Dec. 31, 2015	33,467,893
Balance at Beginning of Period at Dec. 31, 2015	$ 331	$ 946	$ 503,529	$ 233,604	$ 191	$ 738,601
Net Income				23,322		23,322
Other comprehensive gain, net of tax					(1,238)	(1,238)
Stock-based compensation			1,430			1,430
Issuance of common stock related to options exercised, net of shares withheld for payroll taxes (in shares)	15,915
Issuance of common stock related to options exercised, net of shares withheld for payroll taxes			159			159
Vesting of restricted stock awards issued at date of grant, net of shares withheld for payroll taxes (in shares)	(10,434)
Vesting of restricted stock awards issued at date of grant, net of shares withheld for payroll taxes	$ 2		(2)
Restricted stock awards granted (in shares)	104,775
Restricted stock awards granted
Issuance of common stock related to employee stock purchase plan (in shares)	3,450
Issuance of common stock related to employee stock purchase plan			157			157
Balance (in shares) at Mar. 31, 2016	33,581,599
Balance at End of Period at Mar. 31, 2016	$ 333	946	505,338	256,926	(1,047)	762,496
Tax benefits realized from stock compensation			65			65
Balance (in shares) at Dec. 31, 2016	34,023,850
Balance at Beginning of Period at Dec. 31, 2016	$ 338		513,531	331,311	(2,381)	842,799
Net Income				27,017		27,017
Other comprehensive gain, net of tax					1,100	1,100
Stock-based compensation			1,856			1,856
Issuance of common stock related to options exercised, net of shares withheld for payroll taxes (in shares)	2,675
Issuance of common stock related to options exercised, net of shares withheld for payroll taxes			66			66
Vesting of restricted stock awards issued at date of grant, net of shares withheld for payroll taxes (in shares)	(11,788)
Vesting of restricted stock awards issued at date of grant, net of shares withheld for payroll taxes	$ 1		(2)			(1)
Restricted stock awards granted (in shares)	91,097
Restricted stock awards granted
Issuance of common stock related to employee stock purchase plan (in shares)	4,222
Issuance of common stock related to employee stock purchase plan			205			205
Balance (in shares) at Mar. 31, 2017	34,110,056
Balance at End of Period at Mar. 31, 2017	$ 339		$ 515,656	$ 358,328	$ (1,281)	$ 873,042