Mortgage Servicing Rights - Unpaid Principal Loan Balance of Servicing Portfolio (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Unpaid Principal Balance Of Servicing Portfolio [Line Items]
Unpaid principal loan balance	$ 4,761,832	$ 4,036,165
Federal National Mortgage Association
Financing Receivable, Unpaid Principal Balance Of Servicing Portfolio [Line Items]
Unpaid principal loan balance	2,352,981	2,117,703
Federal Home Loan Mortgage Corporation
Financing Receivable, Unpaid Principal Balance Of Servicing Portfolio [Line Items]
Unpaid principal loan balance	1,512,858	948,934
Government National Mortgage Association
Financing Receivable, Unpaid Principal Balance Of Servicing Portfolio [Line Items]
Unpaid principal loan balance	759,524	722,138
Federal Home Loan Bank
Financing Receivable, Unpaid Principal Balance Of Servicing Portfolio [Line Items]
Unpaid principal loan balance	134,616	245,246
Other
Financing Receivable, Unpaid Principal Balance Of Servicing Portfolio [Line Items]
Unpaid principal loan balance	$ 1,853	$ 2,144