Summary of Significant Accounting Policies - Narrative (Details) $ in Thousands		3 Months Ended
		Mar. 31, 2023 USD ($) Segment	Dec. 31, 2022 USD ($)	Mar. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of reportable segments | Segment		1
Retained earnings		$ 510,793	$ 512,099	$ 494,161	$ 490,076
Deferred income taxes		15,548	13,674
Off-balance-sheet credit exposure		3,502	85
Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for loan losses			15,000
Retained earnings	[1]		(11,548)
Deferred income taxes			3,100
Off-balance-sheet credit exposure			3,077
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings		$ 129,617	133,114	$ 99,206	$ 91,043
Retained Earnings | Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings	[1]		$ (11,548)

[1] The Corporation adopted ASU 2016-13 "Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments" effective January 1, 2023. See "Note 1 - Summary of Significant Accounting Policies" for further details.