Comprehensive Income (Loss), Net of Tax - Changes in Accumulated Other Comprehensive Income By Component (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2017
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 269,584	$ 249,603	$ 232,852
Other comprehensive income before reclassifications	6,776	(5,287)	(726)
Amounts reclassified from accumulated other comprehensive income	677	322	691
Other Comprehensive Income (Loss)	7,453	(4,965)	(35)
Amounts reclassified from accumulated other comprehensive loss		(331)
Ending balance	301,728	269,584	249,603
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(3,697)	(1,250)	(382)
Other comprehensive income before reclassifications	4,162	(2,116)	(940)
Amounts reclassified from accumulated other comprehensive income		0	337
Other Comprehensive Income (Loss)	4,162	(2,116)	(603)
Amounts reclassified from accumulated other comprehensive loss		(331)
Ending balance	465	(3,697)	(1,250)
Accumulated Defined Benefit Plans Adjustment, Net Unamortized Gain (Loss) Attributable to Parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(8,971)	(6,380)	(5,737)
Other comprehensive income before reclassifications	2,614	(2,833)	214
Amounts reclassified from accumulated other comprehensive income	510	242	362
Other Comprehensive Income (Loss)	3,124	(2,591)	576
Amounts reclassified from accumulated other comprehensive loss		0
Ending balance	(5,847)	(8,971)	(6,380)
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(1,142)	(884)	(715)
Other comprehensive income before reclassifications	0	(338)	0
Amounts reclassified from accumulated other comprehensive income	167	80	(8)
Other Comprehensive Income (Loss)	167	(258)	(8)
Amounts reclassified from accumulated other comprehensive loss		0
Ending balance	(975)	(1,142)	(884)
Accumulated Other Comprehensive Income (Loss)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(13,810)	(8,514)	(6,834)
Other Comprehensive Income (Loss)	7,453	(4,965)	(35)
Ending balance	$ (6,357)	$ (13,810)	$ (8,514)
Accounting Standards Update 2018-02 | AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Impact of ASU adoption				$ (265)
Accounting Standards Update 2018-02 | Accumulated Defined Benefit Plans Adjustment, Net Unamortized Gain (Loss) Attributable to Parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Impact of ASU adoption				(1,219)
Accounting Standards Update 2018-02 | Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Impact of ASU adoption				(161)
Accounting Standards Update 2018-02 | Accumulated Other Comprehensive Income (Loss)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Impact of ASU adoption				$ (1,645)