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, 2024 USD ($) Y	Dec. 31, 2023 USD ($) Y
MSR and pool characteristics
Carrying value	$ 7,923,078,000	$ 7,099,348,000
Mortgage servicing liabilities | Level 3
Prepayment speed
Annual per-loan cost of servicing	986	1,043
Total | Mortgage servicing rights | Level 3
MSR and pool characteristics
Carrying value	7,923,078,000	7,099,348,000
Unpaid principal balance of underlying loans	$ 396,429,820,000	$ 370,244,119,000
Weighted-average note interest rate (as a percent)	4.30%	4.10%
Weighted-average servicing fee rate (as a percent)	0.39%	0.38%
Pricing spread
Effect on fair value of 5% adverse change	$ (102,124,000)	$ (94,307,000)
Effect on fair value of 10% adverse change	(201,624,000)	(186,129,000)
Effect on fair value of 20% adverse change	(393,121,000)	(362,671,000)
Prepayment speed
Effect on fair value of 5% adverse change	(118,584,000)	(107,757,000)
Effect on fair value of 10% adverse change	(233,004,000)	(211,643,000)
Effect on fair value of 20% adverse change	(450,229,000)	(408,638,000)
Annual per-loan cost of servicing
Effect on fair value of 5% adverse change	(46,108,000)	(44,572,000)
Effect on fair value of 10% adverse change	(92,216,000)	(89,145,000)
Effect on fair value of 20% adverse change	(184,432,000)	(178,289,000)
Total | Mortgage servicing rights | Level 3 | Minimum
Prepayment speed
Annual per-loan cost of servicing	68	70
Total | Mortgage servicing rights | Level 3 | Maximum
Prepayment speed
Annual per-loan cost of servicing	131	135
Total | Mortgage servicing rights | Level 3 | Weighted average
Prepayment speed
Annual per-loan cost of servicing	$ 106	$ 107
Total | Mortgage servicing rights | Annual total prepayment speed | Level 3 | Minimum
Inputs
Input	0.060	0.061
Total | Mortgage servicing rights | Annual total prepayment speed | Level 3 | Maximum
Inputs
Input	0.174	0.178
Total | Mortgage servicing rights | Annual total prepayment speed | Level 3 | Weighted average
Inputs
Input	0.079	0.083
Total | Mortgage servicing rights | Life | Level 3 | Minimum
Inputs
Input | Y	2.9	3.0
Total | Mortgage servicing rights | Life | Level 3 | Maximum
Inputs
Input | Y	9.0	9.0
Total | Mortgage servicing rights | Life | Level 3 | Weighted average
Inputs
Input | Y	8.2	8.1
Total | Mortgage servicing rights | Pricing spread | Level 3 | Minimum
Inputs
Input	0.053	0.055
Total | Mortgage servicing rights | Pricing spread | Level 3 | Maximum
Inputs
Input	0.113	0.126
Total | Mortgage servicing rights | Pricing spread | Level 3 | Weighted average
Inputs
Input	0.063	0.064