Mortgage Servicing Rights - Summary of Carrying Value Under the Amortization Method (Details) - Mortgage Servicing Rights - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Mortgage Servicing Rights Accounted for Under the Amortization Method (Rollforward)
Balance at Beginning of Period	$ 20,598	$ 21,836	$ 18,694	$ 23,896
Servicing Rights that Resulted From Asset Transfers	1,082	872	4,022	3,042
Amortization	(1,069)	(1,271)	(3,228)	(3,684)
Valuation Allowance Recovery (Provision)	662	(568)	1,785	(2,385)
Balance at End of Period	21,273	20,869	21,273	20,869
Balance at Beginning of Period	(2,769)	(1,817)	(3,892)
Valuation Allowance Recovery (Provision)	662	(568)	1,785	(2,385)
Balance at End of Period	(2,107)	(2,385)	(2,107)	(2,385)
Fair Value of Mortgage Servicing Rights Accounted for Under the Amortization Method
Beginning of Period	20,598	21,836	18,694	25,714
End of Period	$ 21,273	$ 20,870	$ 21,273	$ 20,870