Consolidated Statements Of Changes In Shareholders' Equity - USD ($)		Total	Common Stock	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning Balance (in shares) at Dec. 31, 2013			11,369,870
Beginning Balance at Dec. 31, 2013		$ 231,096,000	$ 47,783,000	$ 195,660,000	$ (12,347,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		24,570,000		24,570,000
Other comprehensive income, net of tax		3,922,000			3,922,000
Stock-based compensation expense		599,000	$ 599,000
Exercise of stock options and issuance of restricted stock, net of repurchase for tax withholdings and tax benefit (in shares)			41,496
Exercise of stock options and issuance of vested share awards, net of repurchase for tax withholdings and tax benefit		328,000	$ 328,000
Common stock repurchased (in shares)			(272,033)
Common stock repurchased		(7,155,000)	$ (7,155,000)
Cash dividends declared ( $0.74, $0.80 and $0.83 per share in 2016, 2015, and 2014, respectively)	[1]	(8,251,000)		(8,251,000)
Equity issuance costs		0
SBM acquisition common stock issuance (in shares)			4,124,643
Ending Balance (in shares) at Dec. 31, 2014			11,139,333
Ending Balance at Dec. 31, 2014		245,109,000	$ 41,555,000	211,979,000	(8,425,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		20,952,000		20,952,000
Other comprehensive income, net of tax		(3,797,000)			(3,797,000)
Stock-based compensation expense		836,000	$ 836,000
Exercise of stock options and issuance of restricted stock, net of repurchase for tax withholdings and tax benefit (in shares)			66,741
Exercise of stock options and issuance of vested share awards, net of repurchase for tax withholdings and tax benefit		753,000	$ 753,000
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs		(612,000)	(612,000)
Cash dividends declared ( $0.74, $0.80 and $0.83 per share in 2016, 2015, and 2014, respectively)	[1]	(10,602,000)		(10,602,000)
Equity issuance costs		(612,000)
SBM acquisition common stock issuance		108,561,000	108,561,000
SBM acquisition non-qualified stock option awards		1,990,000	$ 1,990,000
Ending Balance (in shares) at Dec. 31, 2015			15,330,717.000
Ending Balance at Dec. 31, 2015		363,190,000	$ 153,083,000	222,329,000	(12,222,000)
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income			$ 72,000	(72,000)
Stock Issued During Period, Shares, Stock Splits			(173)
Stockholders' Equity Note, Stock Split, Reduction of Capital		(5,000)	$ (5,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		40,067,000		40,067,000
Other comprehensive income, net of tax		(1,687,000)			(1,687,000)
Stock-based compensation expense		1,997,000	$ 1,997,000
Exercise of stock options and issuance of restricted stock, net of repurchase for tax withholdings and tax benefit (in shares)			145,835
Exercise of stock options and issuance of vested share awards, net of repurchase for tax withholdings and tax benefit		894,000	$ 894,000
Cash dividends declared ( $0.74, $0.80 and $0.83 per share in 2016, 2015, and 2014, respectively)	[1]	(12,909,000)		(12,909,000)
Equity issuance costs		0
SBM acquisition common stock issuance (in shares)			4,100,000
Ending Balance (in shares) at Dec. 31, 2016			15,476,379.000
Ending Balance at Dec. 31, 2016		$ 391,547,000	$ 156,041,000	$ 249,415,000	$ (13,909,000)

[1] (1) Share and per share amounts have been adjusted to reflect the three-for-two stock split effective September 30, 2016, for all periods presented. Refer to Note 13 for further discussion.