Fair Value - Level 3 Unobservable Inputs, Mortgage Servicing Rights, Effect of Change In Inputs on Fair Value (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2025 USD ($) Y	Dec. 31, 2024 USD ($) Y
MSR and pool characteristics
Carrying value	$ 8,963,889,000	$ 8,744,528,000
Mortgage servicing liabilities | Level 3
Prepayment speed
Annual per-loan cost of servicing	935	969
Total | Mortgage servicing rights | Level 3
MSR and pool characteristics
Carrying value	8,963,889,000	8,744,528,000
Unpaid principal balance of underlying loans	$ 442,208,097,000	$ 426,055,220,000
Weighted-average note interest rate (as a percent)	4.60%	4.50%
Weighted-average servicing fee rate (as a percent)	0.38%	0.38%
Pricing spread
Effect on fair value of 5% adverse change	$ (114,388,000)	$ (113,419,000)
Effect on fair value of 10% adverse change	(225,908,000)	(223,960,000)
Effect on fair value of 20% adverse change	(440,737,000)	(436,805,000)
Prepayment speed
Effect on fair value of 5% adverse change	(143,098,000)	(126,224,000)
Effect on fair value of 10% adverse change	(281,233,000)	(248,349,000)
Effect on fair value of 20% adverse change	(543,632,000)	(481,100,000)
Annual per-loan cost of servicing
Effect on fair value of 5% adverse change	(49,754,000)	(48,830,000)
Effect on fair value of 10% adverse change	(99,509,000)	(97,661,000)
Effect on fair value of 20% adverse change	(199,018,000)	(195,321,000)
Total | Mortgage servicing rights | Level 3 | Minimum
Prepayment speed
Annual per-loan cost of servicing	68	68
Total | Mortgage servicing rights | Level 3 | Maximum
Prepayment speed
Annual per-loan cost of servicing	127	130
Total | Mortgage servicing rights | Level 3 | Weighted average
Prepayment speed
Annual per-loan cost of servicing	$ 105	$ 105
Total | Mortgage servicing rights | Annual total prepayment speed | Level 3 | Minimum
Inputs
Input	0.062	0.059
Total | Mortgage servicing rights | Annual total prepayment speed | Level 3 | Maximum
Inputs
Input	0.186	0.177
Total | Mortgage servicing rights | Annual total prepayment speed | Level 3 | Weighted average
Inputs
Input	0.088	0.078
Total | Mortgage servicing rights | Life | Level 3 | Minimum
Inputs
Input | Y	2.7	2.7
Total | Mortgage servicing rights | Life | Level 3 | Maximum
Inputs
Input | Y	8.8	9.1
Total | Mortgage servicing rights | Life | Level 3 | Weighted average
Inputs
Input | Y	8.1	8.4
Total | Mortgage servicing rights | Pricing spread | Level 3 | Minimum
Inputs
Input	0.049	0.05
Total | Mortgage servicing rights | Pricing spread | Level 3 | Maximum
Inputs
Input	0.114	0.113
Total | Mortgage servicing rights | Pricing spread | Level 3 | Weighted average
Inputs
Input	0.061	0.062