Mortgage Servicing Rights and Related Liabilities - MSR's at Fair Value (Details) - Mortgage Servicing Rights - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Servicing Asset at Fair Value, Amount [Roll Forward]
Balance - beginning of year	$ 9,090	$ 6,654
Servicing retained from mortgage loans sold	460	273
Purchases and acquisitions of servicing rights	3,004	3,189
Sales of servicing assets and excess yield	(583)	(573)
Changes in valuation inputs or assumptions used in the valuation model (MSR MTM)	650	121
Changes in valuation due to amortization	(923)	(604)
Other changes(1)	38	30
Balance - end of year	$ 11,736	$ 9,090