Comprehensive Income Changes in Accumulated Other Comprehensive Income By Component (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Stockholders' equity, beginning balance	$ 276,609	$ 252,734	$ 269,584	$ 249,603
Other comprehensive income before reclassifications	1,744	(635)
Amounts reclassified from accumulated other comprehensive income	176	116
Other Comprehensive Loss	1,920	(519)	4,163	(2,959)
Stockholders' equity, ending balance	284,649	259,488	284,649	259,488
Total
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Stockholders' equity, beginning balance	(11,567)	(11,285)	(13,810)	(8,514)
Other comprehensive income before reclassifications			3,824	(3,120)
Amounts reclassified from accumulated other comprehensive income			339	161
Other Comprehensive Loss	1,920	(519)	4,163	(2,959)
Amounts reclassified from accumulated other comprehensive income				(331)
Stockholders' equity, ending balance	(9,647)	(11,804)	(9,647)	(11,804)
Unrealized Gains and Losses on Available for Sale Securities
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Stockholders' equity, beginning balance	(1,617)	(4,066)	(3,697)	(1,250)
Other comprehensive income before reclassifications	1,744	(635)	3,824	(3,120)
Amounts reclassified from accumulated other comprehensive income		0	0	0
Other Comprehensive Loss	1,744	(635)	3,824	(3,120)
Amounts reclassified from accumulated other comprehensive income				(331)
Stockholders' equity, ending balance	127	(4,701)	127	(4,701)
Net Actuarial Gain (Loss)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Stockholders' equity, beginning balance	(8,850)	(6,334)	(8,971)	(6,380)
Other comprehensive income before reclassifications	0	0	0	0
Amounts reclassified from accumulated other comprehensive income	133	75	254	121
Other Comprehensive Loss	133	75	254	121
Stockholders' equity, ending balance	(8,717)	(6,259)	(8,717)	(6,259)
Net Priot Service (Cost) Credit
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Stockholders' equity, beginning balance	(1,100)	(885)	(1,142)	(884)
Other comprehensive income before reclassifications	0	0	0	0
Amounts reclassified from accumulated other comprehensive income	43	41	85	40
Other Comprehensive Loss	43	41	85	40
Stockholders' equity, ending balance	$ (1,057)	$ (844)	$ (1,057)	$ (844)

Amount after tax, before reclassification adjustments of other comprehensive income (loss).

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