Mortgage Servicing Rights - Changes in Fair Value of Capitalized MSRs (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Servicing Asset at Fair Value, Amount [Roll Forward]
Balance at beginning of period	$ 3,326	$ 3,633	$ 3,377	$ 3,755
Rights purchased	0	1	1	3
Rights capitalized	72	106	191	301
Rights sold	1	(292)	(188)	(440)
Changes in fair value of MSRs
Due to fluctuations in market interest rates	(121)	219	27	265
Due to revised assumptions or models	3	16	44	0
Other changes in fair value	(94)	(101)	(265)	(302)
Balance at end of period	$ 3,187	$ 3,582	$ 3,187	$ 3,582