Fair Value Option Elected, Difference Between the Aggregate Fair Value and the Aggregate Unpaid Principal Balance (Detail) - USD ($) $ in Millions		3 Months Ended				6 Months Ended
		Jun. 30, 2015		Jun. 30, 2014		Jun. 30, 2015		Jun. 30, 2014		Dec. 31, 2014
Trading assets	[1]	$ 6,438				$ 6,438				$ 6,202
Loans Held-for-sale, Fair Value Disclosure		1,866				1,866				1,892
Loans Receivable, Fair Value Disclosure		263				263				272
Long-term Debt, Fair Value		1,263				1,263				1,283
Aggregate Fair Value Under Fair Value Option
Trading assets		2,668				2,668				2,610
Loans Held-for-sale, Fair Value Disclosure		1,865				1,865				1,891
Loans Receivable, Fair Value Disclosure		261				261				269
Long-term Debt, Fair Value		1,263				1,263				1,283
Aggregate Unpaid Principal Balance Under Fair Value Option
Trading assets		2,610				2,610				2,589
Loans Held-for-sale, Fair Value Disclosure		1,830				1,830				1,817
Loans Receivable, Fair Value Disclosure		274				274				281
Long-term Debt, Fair Value		1,176				1,176				1,176
Fair Value Over/(Under) Unpaid Principal
Trading assets		58				58				21
Loans Held-for-sale, Fair Value Disclosure		35				35				74
Loans Receivable, Fair Value Disclosure		(13)				(13)				(12)
Long-term Debt, Fair Value		87				87				107
Loans Held For Investment [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)		0		$ 4	[2]	2	[3]	$ 8	[2]
Loans Held For Investment [Member] | Aggregate Fair Value Under Fair Value Option
Nonaccrual loans		2				2				3
Loans Held For Investment [Member] | Aggregate Unpaid Principal Balance Under Fair Value Option
Nonaccrual loans		3				3				5
Loans Held For Investment [Member] | Fair Value Over/(Under) Unpaid Principal
Fair Value, Option, Loans Held as Assets, Aggregate Amount in Nonaccrual Status, Aggregated Difference		(1)				(1)				(2)
Loans Held For Sale [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)		(24)	[3]	15	[2]	(12)	[3]	14	[2]
Loans Held For Sale [Member] | Aggregate Fair Value Under Fair Value Option
Nonaccrual loans		1				1				1
Loans Held For Sale [Member] | Aggregate Unpaid Principal Balance Under Fair Value Option
Nonaccrual loans		2				2				1
Loans Held For Sale [Member] | Fair Value Over/(Under) Unpaid Principal
Fair Value, Option, Loans Held as Assets, Aggregate Amount in Nonaccrual Status, Aggregated Difference		(1)				(1)				$ 0
Deposits [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)	[2]			2				5
Mortgage Servicing Income [Member] | Loans Held For Investment [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)		0		0		0		0
Mortgage Servicing Income [Member] | Loans Held For Sale [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)		$ 0		0		$ 0		0
Mortgage Servicing Income [Member] | Deposits [Member]
Fair Value, Option, Changes in Fair Value, Gain (Loss)				$ 0				$ 0

[1] Includes trading securities pledged as collateral where counterparties have the right to sell or repledge the collateral of $1,481 million and $1,316 million at June 30, 2015 and December 31, 2014, respectively

[2] Changes in fair value for the three and six months ended June 30, 2014 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.

[3] Changes in fair value for the three and six months ended June 30, 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.