Tax Effects on Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018		Dec. 31, 2017
Pre-Tax Amount
Other Comprehensive Income	$ 14,537	$ (497)		$ (6,267)
Tax (Expense) Benefit
Other Comprehensive Loss	(3,100)	106		1,624
Net of Tax Amount
Other comprehensive income (loss)	11,437	(391)		(4,643)
Accumulated Net Investment Gain (Loss) Attributable to Parent
Pre-Tax Amount
Net change in unrealized (losses)/gains on debt securities available-for sale	15,793	(6,794)	[1]	(1,275)
Net available-for-sale securities losses reclassified into earnings	26	0		(3,000)
Tax (Expense) Benefit
Net change in unrealized (losses)/gains on debt securities available-for sale	(3,367)	1,449	[1]	448
Net available-for-sale securities losses reclassified into earnings	(6)	0		1,054
Net of Tax Amount
Net change in unrealized (losses)/gains on debt securities available-for sale	12,426	(5,345)	[1]	(827)
Net available-for-sale securities losses reclassified into earnings	20	0		(1,946)
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent
Pre-Tax Amount
Other Comprehensive Income	(1,282)	6,297		(1,992)
Tax (Expense) Benefit
Other Comprehensive Loss	273	(1,343)		122
Net of Tax Amount
Other comprehensive income (loss)	$ (1,009)	$ 4,954		$ (1,870)

[1] Due to the adoption of ASU No. 2016-01, net unrealized gains on marketable equity securities were reclassified from accumulated other comprehensive income to retained earnings during the three months ended March 31, 2018. The prior period data was not restated; as such, the change in unrealized gains on marketable securities is combined with the change in net unrealized gains on debt securities for the prior period ended December 31, 2017.