Mortgage Servicing Rights - Changes in Fair Value of Capitalized MSRs (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Transfers and Servicing of Financial Assets [Abstract]
Balance at beginning of period	$ 3,724	$ 3,432	$ 3,755	$ 2,953
Rights purchased	1	3	2	6
Rights capitalized	99	102	195	339
Rights sold	(149)		(148)	1
Changes in fair value of MSRs
Due to fluctuations in market interest rates	84	289	46	657
Due to revised assumptions or models	(21)	6	(16)	(21)
Other changes in fair value	$ (105)	$ (125)	$ (201)	$ (228)
Servicing Asset, Fair Value, Change in Fair Value, Other, Statement of Income or Comprehensive Income [Extensible Enumeration]	Fees and Commissions, Mortgage Banking and Servicing	Fees and Commissions, Mortgage Banking and Servicing	Fees and Commissions, Mortgage Banking and Servicing	Fees and Commissions, Mortgage Banking and Servicing
Balance at end of period	$ 3,633	$ 3,707	$ 3,633	$ 3,707