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		1
Acquisition of treasury stock					(1,464)
Shares issued under employee benefit plans					406
Shares issued under employee benefit plans (value)		(164)
Net income			5,737			$ 5,737
Additional minimum pension liability, net of tax				42
Unrealized holding gains (losses) arising during period, net of tax				1,522
Reclassification adjustment for (gains) losses included in net income, net of tax				(289)
Balance at Jun. 30, 2018	3,757	123,017	156,585	(865)	(25,585)	256,909
Balance at Mar. 31, 2018	3,757	123,224	151,495	(2,419)	(24,904)
Equity based compensation		(43)
Acquisition of treasury stock					(1,087)
Shares issued under employee benefit plans					406
Shares issued under employee benefit plans (value)		(164)
Net income			5,090			5,090
Additional minimum pension liability, net of tax				21
Unrealized holding gains (losses) arising during period, net of tax				1,834
Reclassification adjustment for (gains) losses included in net income, net of tax				(301)
Balance at Jun. 30, 2018	3,757	123,017	156,585	(865)	(25,585)	256,909
Balance at Dec. 31, 2018	3,757	123,168	161,195	(6,660)	(25,928)	255,532
Equity based compensation		197
Acquisition of treasury stock					(1,380)
Shares issued under employee benefit plans					2,107
Shares issued under employee benefit plans (value)		(587)
Net income			28,054			28,054
Additional minimum pension liability, net of tax				57
Unrealized holding gains (losses) arising during period, net of tax				8,874
Reclassification adjustment for (gains) losses included in net income, net of tax				(3,318)
Balance at Jun. 30, 2019	3,757	122,778	189,249	(1,047)	(25,201)	289,536
Balance at Mar. 31, 2019	3,757	122,638	176,220	(3,762)	(25,201)
Equity based compensation		140
Net income			13,029			13,029
Additional minimum pension liability, net of tax				29
Unrealized holding gains (losses) arising during period, net of tax				2,733
Reclassification adjustment for (gains) losses included in net income, net of tax				(47)
Balance at Jun. 30, 2019	$ 3,757	$ 122,778	$ 189,249	$ (1,047)	$ (25,201)	$ 289,536