Allowance for Loss - Sharing Obligations (Details) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Dec. 31, 2021 USD ($)
Roll forward of loss contingency accrual
Provisions for loss sharing	$ 412	$ (3,272)	$ (2,199)	$ (1,070)
Guarantee obligations	34,200	34,400	$ 34,200	34,400
Percentage of total Fannie Mae servicing portfolio			0.11		0.11
Allowance for loss sharing obligations	19,300		$ 19,300		$ 21,700
Impact of adopting CECL	600		2,400
Allowance for Loan and Lease Loss, Recovery of Bad Debts	1,200
Loss-Sharing Obligation
Roll forward of loss contingency accrual
Outstanding advances under the Fannie Mae DUS program	400		400		100
Loss-Sharing Obligation | Fannie Mae Mortgage
Roll forward of loss contingency accrual
Beginning balance	53,053	65,645	56,064	64,303	64,303
Provisions for loss sharing	2,346	(3,022)	2,593	(557)
Provisions reversal for loan repayments	(1,934)	(250)	(4,792)	(513)
Recoveries (charge-offs), net	46	455	(354)	(405)
Ending balance	53,511	$ 62,828	53,511	$ 62,828	56,064
Maximum quantifiable liability	$ 3,420,000		$ 3,420,000		$ 3,600,000