Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Total
Cumulative effect of adoption of updated accounting guidance for equity financial instruments at January 1,2018 | Accounting Standards Update 2016-01 [Member]			$ 16,993	$ (16,993)
Reclassification of certain tax effects from accumulated other comprehensive income at January 1,2018			(2,619)	2,619
Balance at Dec. 31, 2017	$ 3,757	$ 123,180	136,474	12,234	$ (24,527)
Equity based compensation		37
Acquisition of treasury stock					(1,464)
Shares issued under employee benefit plans					406
Shares issued under employee benefit plans (value)		(164)
Net income			15,422			$ 15,422
Additional minimum pension liability, net of tax				63
Unrealized holding gains arising during period, net of tax				1,508
Reclassification adjustment for (gains) losses included in net income, net of tax				126
Balance at Sep. 30, 2018	3,757	123,053	166,270	(443)	(25,585)	267,052
Balance at Jun. 30, 2018	3,757	123,017	156,585	(865)	(25,585)
Equity based compensation		36
Net income			9,685			9,685
Additional minimum pension liability, net of tax				21
Unrealized holding gains arising during period, net of tax				270
Reclassification adjustment for (gains) losses included in net income, net of tax				131
Balance at Sep. 30, 2018	3,757	123,053	166,270	(443)	(25,585)	267,052
Balance at Dec. 31, 2018	3,757	123,168	161,195	(6,660)	(25,928)	255,532
Equity based compensation		514
Acquisition of treasury stock					(1,380)
Shares issued under employee benefit plans					2,107
Shares issued under employee benefit plans (value)		(587)
Net income			33,341			33,341
Additional minimum pension liability, net of tax				85
Unrealized holding gains arising during period, net of tax				10,278
Reclassification adjustment for (gains) losses included in net income, net of tax				(3,457)
Balance at Sep. 30, 2019	3,757	123,095	194,536	246	(25,201)	296,433
Balance at Jun. 30, 2019	3,757	122,778	189,249	(1,047)	(25,201)
Equity based compensation		317
Net income			5,287			5,287
Additional minimum pension liability, net of tax				28
Unrealized holding gains arising during period, net of tax				1,404
Reclassification adjustment for (gains) losses included in net income, net of tax				(139)
Balance at Sep. 30, 2019	$ 3,757	$ 123,095	$ 194,536	$ 246	$ (25,201)	$ 296,433