Change in Fair Value of Financial Instruments for which the FVO has been Elected (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016		Mar. 31, 2015
Mortgage Servicing Rights [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	$ 247	[1]	$ 125	[2]
Mortgage Servicing Rights [Member] | Other Income [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	0
Mortgage Servicing Rights [Member] | Trading Revenue [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	0		0
Mortgage Servicing Rights [Member] | Mortgage Production Income [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	0	[3]	(1)	[4]
Mortgage Servicing Rights [Member] | Mortgage Servicing Income [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	247		126
Long-term Debt [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	2	[1]	(1)	[2]
Long-term Debt [Member] | Other Income [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	0
Long-term Debt [Member] | Trading Revenue [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	2		(1)
Long-term Debt [Member] | Mortgage Production Income [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	0	[3]	0	[4]
Long-term Debt [Member] | Mortgage Servicing Income [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	0		0
Loans Held For Investment [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	(3)	[1]	(2)	[2]
Loans Held For Investment [Member] | Other Income [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	(3)
Loans Held For Investment [Member] | Trading Revenue [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	0		0
Loans Held For Investment [Member] | Mortgage Production Income [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	0	[3]	(2)	[4]
Loans Held For Investment [Member] | Mortgage Servicing Income [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	0		0
Loans Held For Sale [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	(55)	[1]	(12)	[2]
Loans Held For Sale [Member] | Other Income [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	0
Loans Held For Sale [Member] | Trading Revenue [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	0		0
Loans Held For Sale [Member] | Mortgage Production Income [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	(55)	[3]	(12)	[4]
Loans Held For Sale [Member] | Mortgage Servicing Income [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	0		0
Trading Account Assets [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	(6)	[1]	(4)	[2]
Trading Account Assets [Member] | Other Income [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	0
Trading Account Assets [Member] | Trading Revenue [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	(6)		(4)
Trading Account Assets [Member] | Mortgage Production Income [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	0	[3]	0	[4]
Trading Account Assets [Member] | Mortgage Servicing Income [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	$ 0		$ 0

[1] Changes in fair value for the three months ended March 31, 2016 exclude accrued interest for the period then ended. Interest income or interest expense on trading loans, LHFS, LHFI, 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] Changes in fair value for the three months ended March 31, 2015 exclude accrued interest for the period then ended. Interest income or interest expense on trading loans, LHFS, LHFI, 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.

[3] Income related to LHFS does not include income from IRLCs. For the three months ended March 31, 2016, income related to MSRs includes income recognized upon the sale of loans reported at LOCOM.

[4] Income related to LHFS does not include income from IRLCs. For the three months ended March 31, 2015, income related to MSRs includes income recognized upon the sale of loans reported at LOCOM.