Comprehensive Income - Components of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Accumulated Other Comprehensive Income (AOCI)
Beginning balance			$ 239,483
Other comprehensive income (loss) before reclassification	$ 2,827	$ (329)	(716)	$ 188
Amounts reclassified from AOCI	(936)	374	(1,511)	(1,060)
Total other comprehensive income (loss)	1,891	45	(2,227)	(872)
Ending balance	248,611		248,611
Unrealized gains (losses) on available for-sale securities
Accumulated Other Comprehensive Income (AOCI)
Beginning balance	1,863	3,773	7,586	2,942
Other comprehensive income (loss) before reclassification	2,581	402	(2,267)	1,434
Amounts reclassified from AOCI	(1,308)	(404)	(2,183)	(605)
Total other comprehensive income (loss)	1,273	(2)	(4,450)	829
Ending balance	3,136	3,771	3,136	3,771
Defined benefit pension plan items
Accumulated Other Comprehensive Income (AOCI)
Beginning balance	(3,644)	(4,734)	(5,047)	(4,295)
Other comprehensive income (loss) before reclassification	246	(731)	1,551	(1,246)
Amounts reclassified from AOCI	97	77	195	153
Total other comprehensive income (loss)	343	(654)	1,746	(1,093)
Ending balance	(3,301)	(5,388)	(3,301)	(5,388)
Investment hedge
Accumulated Other Comprehensive Income (AOCI)
Beginning balance	(111)	(1,277)	(313)	32
Other comprehensive income (loss) before reclassification	0	0	0	0
Amounts reclassified from AOCI	275	701	477	(608)
Total other comprehensive income (loss)	275	701	477	(608)
Ending balance	164	(576)	164	(576)
Accumulated other comprehensive income (loss)
Accumulated Other Comprehensive Income (AOCI)
Beginning balance	(1,892)	(2,238)	2,226	(1,321)
Ending balance	$ (1)	$ (2,193)	$ (1)	$ (2,193)