Mortgage Servicing Rights and Mortgage Servicing Liabilities - Mortgage Servicing Liabilities Carried at FV (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Amortized cost:
Mortgage servicing liabilities resulting from loan sales	$ 106,631	$ 23,325	$ 37,988
Mortgage servicing liabilities
Amortized cost:
Balance at beginning of period	45,324	29,140	8,681
Mortgage servicing liabilities resulting from loan sales	106,631	23,325	37,988
Changes in valuation inputs used in valuation model	(68,020)	31,757	8,377
Other changes in fair value	(81,119)	(38,898)	(25,906)
Total change in fair value	(149,139)	(7,141)	(17,529)
Balance at end of period	2,816	45,324	29,140
UPB of underlying loan at end of year	$ 60,593	$ 2,857,492	$ 2,758,454