Consolidated Statements of Comprehensive Income (Loss) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement Of Income And Comprehensive Income [Abstract]
Unrealized income (losses) arising during the period on available for sale securities, tax	$ 51	$ (157)	$ 847	$ (730)
Reclassification adjustment for net gain on sales of available for sale securities included in net income, tax	(9)	(6)	(14)	(28)
Change in defined benefit plans, tax	(61)	66	(145)	422
Reclassification adjustment for settlement gains on benefit plans, tax	$ (4)	$ (25)	$ (21)	$ (105)

Amount, before reclassification adjustment, of tax (expense) benefit for (increase) decrease in accumulated other comprehensive income for defined benefit plan.

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Amount of tax expense (benefit) of reclassification adjustment from accumulated other comprehensive income for unrealized gain (loss) realized upon the sale of available-for-sale securities.

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Amount of tax expense (benefit) of reclassification adjustment from accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan.

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Amount of tax expense (benefit) before reclassification adjustments of unrealized holding gain (loss) on available-for-sale securities.

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