Fair Value - Level 3 Unobservable Inputs, Mortgage Servicing Rights, Effect of Change In Inputs on Fair Value (Details)	6 Months Ended	12 Months Ended
	Jun. 30, 2022 USD ($) item	Dec. 31, 2021 USD ($) item
MSR and pool characteristics
Carrying value	$ 5,217,167,000	$ 3,878,078,000
Mortgage servicing liabilities | Level 3
Prepayment speed
Annual per-loan cost of servicing	1,253	1,406
Total | Mortgage servicing rights | Level 3
MSR and pool characteristics
Carrying value	5,217,167,000	3,878,078,000
Unpaid principal balance of underlying loans	$ 297,269,682,000	$ 278,324,780,000
Weighted-average note interest rate (as a percent)	3.20%	3.20%
Weighted-average servicing fee rate (as a percent)	0.35%	0.34%
Pricing spread
Effect on fair value of 5% adverse change	$ (76,013,000)	$ (59,577,000)
Effect on fair value of 10% adverse change	(149,848,000)	(117,352,000)
Effect on fair value of 20% adverse change	(291,326,000)	(227,791,000)
Prepayment speed
Effect on fair value of 5% adverse change	(79,424,000)	(80,109,000)
Effect on fair value of 10% adverse change	(156,226,000)	(157,252,000)
Effect on fair value of 20% adverse change	(302,462,000)	(303,259,000)
Annual per-loan cost of servicing
Effect on fair value of 5% adverse change	(37,615,000)	(32,979,000)
Effect on fair value of 10% adverse change	(75,231,000)	(65,958,000)
Effect on fair value of 20% adverse change	(150,461,000)	(131,916,000)
Total | Mortgage servicing rights | Level 3 | Minimum
Prepayment speed
Annual per-loan cost of servicing	79	79
Total | Mortgage servicing rights | Level 3 | Maximum
Prepayment speed
Annual per-loan cost of servicing	156	197
Total | Mortgage servicing rights | Level 3 | Weighted average
Prepayment speed
Annual per-loan cost of servicing	$ 106	$ 108
Total | Mortgage servicing rights | Pricing spread | Level 3 | Minimum
Inputs
Input | item	4.9	5.3
Total | Mortgage servicing rights | Pricing spread | Level 3 | Maximum
Inputs
Input | item	14.8	15.5
Total | Mortgage servicing rights | Pricing spread | Level 3 | Weighted average
Inputs
Input | item	6.9	7.7
Total | Mortgage servicing rights | Annual total prepayment speed | Level 3 | Minimum
Inputs
Input | item	5.5	7.9
Total | Mortgage servicing rights | Annual total prepayment speed | Level 3 | Maximum
Inputs
Input | item	19.0	26.7
Total | Mortgage servicing rights | Annual total prepayment speed | Level 3 | Weighted average
Inputs
Input | item	8.2	10.7
Total | Mortgage servicing rights | Life | Level 3 | Minimum
Inputs
Input | item	2.0	3.1
Total | Mortgage servicing rights | Life | Level 3 | Maximum
Inputs
Input | item	9.2	7.7
Total | Mortgage servicing rights | Life | Level 3 | Weighted average
Inputs
Input | item	8.0	6.8