Stockholders' Equity and Earnings per Common Share, Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		$ 93,990		$ 93,176	$ 88,497
Ending Balance		96,388		93,990	93,176
Other comprehensive income, pretax [Abstract]
Unrealized holding gains (losses) arising during the period, pretax		1,659		(1,240)	(679)
Reclassification adjustment for gains (loss) recognized in income, pretax		(96)		(522)	(76)
Net unrealized gains (losses) on securities		1,563		(1,762)	(755)
Elimination upon transfer back to available-for-sale, pretax					4,197
Amortization, pretax					934
Net change, pretax					5,131
Plan termination, settlement and net amortization, pretax		3,741
Net actuarial income (loss) for the period, pretax		(99)		(327)	(627)
Amortization of actuarial gain (loss) from prior period, pretax	[1]	490		504	390
Net change, pretax		3,741		177	(237)
Total change in accumulated other comprehensive income or (loss), pretax		5,304		(1,585)	4,139
Other Comprehensive Income Tax Effect [Abstract]
Unrealized holding gains (losses) arising during the period, tax effect		564		(422)	(231)
Reclassification adjustment for gains (losses) recognized in income, tax effect		(33)		(177)	(26)
Net unrealized losses on securities, tax effect		531		(599)	(257)
Elimination upon transfer back to available-for-sale, tax effect					1,427
Amortization, tax effect					318
Net change, tax effect					1,745
Plan termination, settlement and net amortization, tax effect		1,272
Net actuarial loss for the period, tax effect				(111)	(213)
Amortization of actuarial gain (loss) from prior period, tax effect		167		171	133
Net change, tax effect				60	(80)
Total change in other comprehensive income or (loss), tax effect		1,803		(539)	1,408
Other Comprehensive Income, Net of Tax [Abstract]
Unrealized holding gains (losses) arising during the period, net of tax		1,095		(818)	(448)
Reclassification adjustment for gains (losses) recognized in income, net of tax		(63)		(345)	(50)
Net unrealized losses on securities, net of tax		1,032		(1,163)	(498)
Elimination upon transfer back to available-for-sale, net of tax					2,770
Amortization, net of tax					616
Net change, net of tax		0		0	3,386
Plan termination, settlement and net amortization, net of tax		2,469
Net actuarial loss for the period, net of tax				(216)	(414)
Amortization of actuarial gain (loss) from prior period, net of tax		323		333	257
Net change, net of tax		2,469		117	(157)
Total change in other comprehensive income or (loss), net of tax		3,501		(1,046)	2,731
Unrealized Gains (Losses) on Available-for-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		(1,739)		(576)	(78)
Net change for the year		1,032		(1,163)	(498)
Ending Balance		(707)		(1,739)	(576)
Unrealized Losses on Securities Transferred from Available-for-Sale to Held-to-Maturity [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		0		0	(3,386)
Net change for the year		0		0	3,386	[2]
Ending Balance		0		0	0
Defined Benefit Pension Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		(2,469)		(2,586)	(2,429)
Net change for the year		2,469	[3]	117	(157)
Ending Balance		0		(2,469)	(2,586)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		(4,208)		(3,162)	(5,893)
Net change for the year		3,501		(1,046)	2,731
Ending Balance		(707)		(4,208)	(3,162)
Other Comprehensive Income, Net of Tax [Abstract]
Total change in other comprehensive income or (loss), net of tax		$ 3,501		$ (1,046)	$ 2,731

[1] (1) This accumulated other comprehensive loss component is included in the computation of net periodic pension cost (see Note 14. Pension Plan and 401(k) Plan for additional details).

[2] Net change for the year ended December 31, 2015 represents reclassification due to the transfer of securities held-to-maturity to available-for-sale

[3] Net change reflects termination and settlement of pension plan during year ended December 31, 2017