Accumulated Comprehensive Loss, By Component (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance		$ 148,021	$ 132,281	$ 139,229	$ 129,011
Change in Accounting policy for equity securities						$ 0
Other comprehensive income (loss) before reclassifications (net of tax)		7	(766)	3,495	(2,800)
Amounts reclassified from accumulated other comprehensive income (loss) (net of tax)		41	42	137	116
Other comprehensive income (loss), net of tax		48	(724)	3,632	(2,684)
Balance		151,678	134,400	151,678	134,400
Accumulated Other Comprehensive Loss [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance		(337)	(5,357)	(3,921)	(3,398)
Change in Accounting policy for equity securities						1
Other comprehensive income (loss), net of tax		48	(724)	3,632	(2,684)
Balance		(289)	(6,081)	(289)	(6,081)
Unrealized Gain (Loss) on Available for Sale Securities [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance	[1]	2,515	(2,302)	(973)	(269)
Change in Accounting policy for equity securities						1
Other comprehensive income (loss) before reclassifications (net of tax)	[1]	7	(766)	3,495	(2,800)
Amounts reclassified from accumulated other comprehensive income (loss) (net of tax)	[1]	(6)	6	(6)	6
Other comprehensive income (loss), net of tax	[1]	1	(760)	3,489	(2,794)
Balance	[1]	2,516	(3,062)	2,516	(3,062)
Defined Benefit Pension Items [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance	[1]	(2,852)	(3,055)	(2,948)	(3,129)
Change in Accounting policy for equity securities						$ 0
Other comprehensive income (loss) before reclassifications (net of tax)	[1]	0	0	0	0
Amounts reclassified from accumulated other comprehensive income (loss) (net of tax)	[1]	47	36	143	110
Other comprehensive income (loss), net of tax	[1]	47	36	143	110
Balance	[1]	$ (2,805)	$ (3,019)	$ (2,805)	$ (3,019)

[1] Amounts in parentheses indicate debits on the Consolidated Balance Sheet.