Change in Fair Value of Financial Instruments for which the FVO has been Elected (Detail) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2019		Jun. 30, 2018		Jun. 30, 2019		Jun. 30, 2018
Trading Loans [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	$ 12	[1],[2]	$ 5	[3],[4]	$ 19	[1],[2]	$ 7	[3],[4]
Trading Loans [Member] | Trading Revenue [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	12	[2]	5	[4]	19	[2]	7	[4]
Trading Loans [Member] | Mortgage Related Income [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	0	[5]	0	[6]	0	[5]	0	[6]
Trading Loans [Member] | Other Income [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	0		0		0		0
Loans Held-For-Sale [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	25	[1],[2]	5	[3],[7]	40	[1],[8]	(8)	[3],[7]
Loans Held-For-Sale [Member] | Trading Revenue [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	0		0		0		0
Loans Held-For-Sale [Member] | Mortgage Related Income [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	25	[5],[8]	5	[6],[7]	40	[5],[8]	(8)	[6],[7]
Loans Held-For-Sale [Member] | Other Income [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	0		0		0		0
Loans Held-For-Investment [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	1	[1]	1	[3]	3	[1]	(3)	[3]
Loans Held-For-Investment [Member] | Trading Revenue [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	0		0		0		0
Loans Held-For-Investment [Member] | Mortgage Related Income [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	0	[5]	1	[6]	0	[5]	0	[6]
Loans Held-For-Investment [Member] | Other Income [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	1		0		3		(3)
Mortgage Servicing Rights [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	(240)	[1]	(29)	[3]	(400)	[1]	30	[3]
Mortgage Servicing Rights [Member] | Trading Revenue [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	0		0		0		0
Mortgage Servicing Rights [Member] | Mortgage Related Income [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	(240)	[5]	(29)	[6]	(400)	[5]	30	[6]
Mortgage Servicing Rights [Member] | Other Income [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	0		0		0		0
Brokered Time Deposits [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	(9)	[1]	(3)	[1]	(21)	[1]	10	[3]
Brokered Time Deposits [Member] | Trading Revenue [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	(9)		(3)		(21)		10
Brokered Time Deposits [Member] | Mortgage Related Income [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	0	[5]	0	[5]	0	[5]	0	[6]
Brokered Time Deposits [Member] | Other Income [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	0		0		0		0
Long-term Debt [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	(6)	[1]	2	[3]	(13)	[1]	5	[3]
Long-term Debt [Member] | Trading Revenue [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	(6)		2		(13)		5
Long-term Debt [Member] | Mortgage Related Income [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	0	[5]	0	[6]	0	[5]	0	[6]
Long-term Debt [Member] | Other Income [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	$ 0		$ 0		$ 0		$ 0

[1] Changes in fair value for the three and six months ended June 30, 2019 exclude accrued interest for the period then ended. Interest income or interest expense on trading loans, LHFS, LHFI, brokered time deposits, and long-term debt that have been elected to be measured at fair value are recognized in Interest income or Interest expense in the Consolidated Statements of Income.

[2] Includes an immaterial amount of gains or losses in the Consolidated Statements of Income due to changes in fair value attributable to instrument-specific credit risk for three and six months ended June 30, 2019.

[3] Changes in fair value for the three and six months ended June 30, 2018 exclude accrued interest for the period then ended. Interest income or interest expense on trading loans, LHFS, LHFI, brokered time deposits, and long-term debt that have been elected to be measured at fair value are recognized in Interest income or Interest expense in the Consolidated Statements of Income.

[4] Includes an immaterial amount of gains or losses in the Consolidated Statements of Income due to changes in fair value attributable to instrument-specific credit risk for three and six months ended June 30, 2018.

[5] Income related to LHFS does not include income from IRLCs. For the three and six months ended June 30, 2019, income related to residential MSRs includes income recognized upon the sale of loans reported at LOCOM.

[6] Income related to LHFS does not include income from IRLCs. For the three and six months ended June 30, 2018, income related to residential MSRs includes income recognized upon the sale of loans reported at LOCOM.

[7] Includes an immaterial amount of gains or losses in the Consolidated Statements of Income due to changes in fair value attributable to borrower-specific credit risk for the three and six months ended June 30, 2018.

[8] Includes an immaterial amount of gains or losses in the Consolidated Statements of Income due to changes in fair value attributable to borrower-specific credit risk for the three and six months ended June 30, 2019.