Mortgage Servicing Rights - Summary of Carrying Value Under the Amortization Method (Details) - Mortgage Servicing Rights - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Mortgage Servicing Rights Accounted for Under the Amortization Method (Rollforward)
Balance at Beginning of Period	$ 18,694	$ 23,896
Servicing Rights that Resulted From Asset Transfers	1,680	1,165
Amortization	(1,163)	(1,112)
Valuation Allowance Recovery (Provision)	2,190	(2,513)
Balance at End of Period	21,401	21,436
Balance at Beginning of Period	(3,892)
Valuation Allowance Recovery (Provision)	2,190	(2,513)
Balance at End of Period	(1,702)	(2,513)
Fair Value of Mortgage Servicing Rights Accounted for Under the Amortization Method
Beginning of Period	18,694	25,714
End of Period	$ 21,401	$ 21,436