Mortgage Servicing Rights and Mortgage Servicing Liabilities - Activity in MSRs at Fair Value (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Change in fair value due to:
Total change in fair value	$ 415,906	$ 1,501,993	$ 988,614
Mortgage servicing rights
Activity in MSRs carried at fair value
Balance at beginning of period	2,581,174	2,926,790	2,820,612
Additions - Resulting from loan sales	1,861,949	1,138,045	884,876
Additions - Purchases (purchase adjustments)		25,473	227,445
Additions	1,861,949	1,163,518	1,112,321
Change in fair value due to:
Changes in valuation inputs used in valuation model	(136,350)	(1,078,084)	(550,666)
Other changes in fair value	(428,695)	(431,050)	(455,477)
Total change in fair value	(565,045)	(1,509,134)	(1,006,143)
Balance at end of period	3,878,078	2,581,174	2,926,790
UPB of underlying loan at end of year	278,324,780	238,410,809	$ 225,787,104
Fair value of mortgage servicing rights pledged to secure Assets sold under agreements to repurchase and Notes payable secured by mortgage servicing assets	$ 3,856,791	$ 2,577,964