CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Thousands		Total		Common Stock	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning Balance (in shares) at Dec. 31, 2015	[1]			15,330,717
Beginning Balance at Dec. 31, 2015		$ 363,190		$ 153,083	$ 222,329	$ (12,222)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		8,646	[2],[3],[4],[5]		8,646
Other comprehensive income, net of tax		5,702				5,702
Stock-based compensation expense		324		$ 324
Exercise of stock options and issuance of vested share awards, net of repurchase for tax withholdings and tax benefit (shares)	[1]			75,766
Exercise of stock options and issuance of vested share awards, net of repurchase for tax withholdings		719		$ 719
Cash dividends declared ($0.20 and $0.23 per share in three months ended March 31, 2016 and March 31, 2017)	[1]	(3,123)			(3,123)
Ending Balance (in shares) at Mar. 31, 2016	[1]			15,406,483
Ending Balance at Mar. 31, 2016		375,458		$ 154,198	227,780	(6,520)
Beginning Balance (in shares) at Dec. 31, 2015	[1]			15,330,717
Beginning Balance at Dec. 31, 2015		363,190		$ 153,083	222,329	(12,222)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect adjustment(2)	[6]			$ 72	(72)
Ending Balance (in shares) at Dec. 31, 2016	[1]			15,476,379
Ending Balance at Dec. 31, 2016		391,547		$ 156,041	249,415	(13,909)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		10,076			10,076
Other comprehensive income, net of tax		(29)				(29)
Stock-based compensation expense		366		$ 366
Exercise of stock options and issuance of vested share awards, net of repurchase for tax withholdings and tax benefit (shares)	[1]			31,646
Exercise of stock options and issuance of vested share awards, net of repurchase for tax withholdings		(552)		$ (552)
Cash dividends declared ($0.20 and $0.23 per share in three months ended March 31, 2016 and March 31, 2017)	[1]	(3,581)			(3,581)
Ending Balance (in shares) at Mar. 31, 2017	[1]			15,508,025.000
Ending Balance at Mar. 31, 2017		$ 397,827		$ 155,855	$ 255,910	$ (13,938)

[1] (1) Share and per share amounts as of December 31, 2015 and as of and for the three months ended March 31, 2016 have been adjusted to reflect the three-for-two stock split effective September 30, 2016.

[2] (1) The financial information for the three months ended March 31, 2016 has been adjusted to reflect the adoption of ASU 2016-09.

[3] (1)The consolidated statement of cash flows for the three months ended March 31, 2016 has been adjusted to reflect the adoption of ASU 2016-09 in the second quarter of 2016 effective as of January 1, 2016.

[4] (1)The consolidated statement of income for the three months ended March 31, 2016 has been adjusted to reflect the adoption of Accounting Standards Updates No. 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting ("ASU 2016-09") in the second quarter of 2016 effective as of January 1, 2016.

[5] (5) Share and per share amounts for the three months ended March 31, 2016 have been adjusted to reflect the three-for-two stock split effective September 30, 2016.

[6] (2)In the second quarter of 2016, the Company adopted ASU 2016-09, effective January 1, 2016. The Company made a policy election to not estimate the forfeiture rate in the accounting for share-based compensation on its unvested share-based awards. The change in policy was accounted for on a modified-retrospective basis and represents the cumulative effect adjustment to shareholders' equity.