Reconciliation of the Beginning and Ending Balances for Fair Valued Assets and Liabilities Measured on a Recurring Basis Using Significant Unobservable Inputs (Detail) - USD ($) $ in Millions		3 Months Ended				9 Months Ended
		Sep. 30, 2015		Sep. 30, 2014		Sep. 30, 2015		Sep. 30, 2014		Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
Loans Held For Sale [Member] | Residential Mortgage, Loans Held For Sale [Member]
Included in earnings		$ 0		$ 0		$ 0		$ 0
OCI		0		0		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0		0		0		0
Sales		(7)		(3)		(16)		(7)
Settlements		0		0		0		0
Transfers to other balance sheet line items		(1)		0		(2)		(6)
Transfers into Level 3		8		1		19		12
Transferred Out of Level 3 in The Fair Value Hierarchy		0		0		0		(1)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		2		1		2		1		$ 2	$ 1	$ 3	$ 3
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income		0		0		0		0
Trading Account Assets [Member]
Included in earnings								192
OCI								0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases								0
Sales								(72)
Settlements								2
Transfers to other balance sheet line items								(185)
Transfers into Level 3								0
Transferred Out of Level 3 in The Fair Value Hierarchy								0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value				5				5					68
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income								(10)
Trading Account Assets [Member] | Asset-backed Securities [Member]
Included in earnings	[1]							1
OCI								0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases								0
Sales								(7)
Settlements								0
Transfers to other balance sheet line items								0
Transfers into Level 3								0
Transferred Out of Level 3 in The Fair Value Hierarchy								0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value				0				0					6
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income								0
Trading Account Assets [Member] | Collateralized Debt Obligations [Member]
Included in earnings	[1]							11
OCI								0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases								0
Sales								(65)
Settlements								0
Transfers to other balance sheet line items								0
Transfers into Level 3								0
Transferred Out of Level 3 in The Fair Value Hierarchy								0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value				0				0					54
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income								0
Trading Assets [Member] | Derivative contracts, net [Member]
Included in earnings		58	[2]	47	[3]	148	[2]	180	[3]
OCI		0		0		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0		0		0		0
Sales		0		0		0		0
Settlements		1		1		2		2
Transfers into Level 3		0		0		0		0
Transferred Out of Level 3 in The Fair Value Hierarchy		0		0		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		32		5		32		5		14	20	21	8
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income		(1)	[2],[4]	16	[3],[5]	(5)	[2],[4]	(10)	[3],[5]
Available-for-sale Securities [Member]
Included in earnings		(1)		(1)		(1)		(3)	[6]
OCI		(1)		(1)		0		5
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		5		135		109		270
Sales		0		0		0		(20)
Settlements		(155)		(97)		(487)		(211)
Transfers to other balance sheet line items		0		6		0		6
Transfers into Level 3		0		0		0		0
Transferred Out of Level 3 in The Fair Value Hierarchy		0		0		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		567		1,000		567		1,000		719	946	958	953
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income		(1)		(1)		(1)		(1)
Available-for-sale Securities [Member] | US States and Political Subdivisions Debt Securities [Member]
Included in earnings		0		0		0		(2)
OCI		0		0		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0		0		0		0
Sales		0		0		0		(20)
Settlements		0		0		(7)		0
Transfers to other balance sheet line items		0		0		0		0
Transfers into Level 3		0		0		0		0
Transferred Out of Level 3 in The Fair Value Hierarchy		0		0		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		5		12		5		12		5	12	12	34
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income		0		0		0		0
Available-for-sale Securities [Member] | Asset-backed Securities [Member]
Included in earnings		0		0		0		0
OCI		0		0		0		1	[7]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0		0		0		0
Sales		0		0		0		0
Settlements		(2)		(1)		(6)		(1)
Transfers to other balance sheet line items		0		0		0		0
Transfers into Level 3		0		0		0		0
Transferred Out of Level 3 in The Fair Value Hierarchy		0		0		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		15		21		15		21		17	21	22	21
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income		0		0		0		0
Available-for-sale Securities [Member] | Other Debt Obligations [Member]
Included in earnings		0		0		0		0
OCI		0		0		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		5		0		5		0
Sales		0		0		0		0
Settlements		(3)		0		(5)		0
Transfers to other balance sheet line items		0		0		0		0
Transfers into Level 3		0		0		0		0
Transferred Out of Level 3 in The Fair Value Hierarchy		0		0		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		5		5		5		5		3	5	5	5
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income		0		0		0		0
Available-for-sale Securities [Member] | Equity Securities [Member]
Included in earnings		0		0		0		0
OCI		(2)	[8]	0		2	[8]	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0		135		104		270
Sales		0		0		0		0
Settlements		(140)		(90)		(447)		(185)
Transfers to other balance sheet line items		0		6		0		6
Transfers into Level 3		0		0		0		0
Transferred Out of Level 3 in The Fair Value Hierarchy		0		0		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		440		830		440		830		582	785	779	739
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income		0		0		0		0
Available-for-sale Securities [Member] | Mortgage-backed Securities, Issued by Private Enterprises [Member]
Included in earnings		(1)		(1)		(1)		(1)
OCI		1	[8]	(1)	[7]	2	[8]	4	[7]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0		0		0		0
Sales		0		0		0		0
Settlements		(10)		(6)		(22)		(25)
Transfers to other balance sheet line items		0		0		0		0
Transfers into Level 3		0		0		0		0
Transferred Out of Level 3 in The Fair Value Hierarchy		0		0		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		102		132		102		132		112	123	140	154
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income		(1)		(1)		(1)		(1)
Loans Held For Investment [Member]
Included in earnings		3	[9]	(1)	[10]	3	[9]	9	[10]
OCI		0		0		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0		0		0		0
Sales		0		0		0		0
Settlements		(8)		(8)		(32)		(31)
Transfers to other balance sheet line items		0		(2)		(1)		3
Transfers into Level 3		4		1		20		1
Transferred Out of Level 3 in The Fair Value Hierarchy		0		0		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		262		284		262		284		263	272	292	302
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income		3	[4],[9]	1	[5],[10]	1	[4],[9]	6	[5],[10]
Other Liabilities [Member]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases		0		0		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Sales		0		0		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements		0		(3)		(10)		(3)
Transfers to other balance sheet line items		0		0		0		(3)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Liabilities Transfers Into Level 3		0		0		0		0
Fair Value Measurement With Unobservable Inputs Reconciliation, Recurring Basis, Liabilities Transfers Out Of Level 3		0		0		0		0
Change in unrealized gains / (losses) included in earnings for the period related to financial assets still held at the end of period		0	[4],[11]	0	[5],[12]	6	[4],[11]	0	[5],[12]
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value		23		24		23		24		$ 23	$ 27	$ 27	$ 29
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings		0		0	[12]	6	[11]	1	[12]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Other Comprehensive Income (Loss)		0		0		0		0
Interest Rate Lock Commitments [Member]
Transferred Out of Level 3 in The Fair Value Hierarchy		(41)		(64)		(138)		(181)
Interest Rate Lock Commitments [Member] | Trading Assets [Member] | Derivative contracts, net [Member]
Transfers to other balance sheet line items		$ (41)		$ (64)		$ (138)		$ (185)

[1] Amounts included in earnings are recognized in trading income.

[2] Includes issuances, fair value changes, and expirations and are recognized in mortgage production related income.

[3] Includes issuances, fair value changes, and expirations and are recognized in mortgage production related income.

[4] Change in unrealized gains/(losses) included in earnings during the period related to financial assets/liabilities still held at September 30, 2015

[5] Change in unrealized gains/(losses) included in earnings for the period related to financial assets/liabilities still held at September 30, 2014

[6] Amounts included in earnings are recognized in net securities gains/(losses).

[7] Amounts recognized in OCI are included in change in net unrealized gains/(losses) on securities AFS, net of tax

[8] Amount recognized in OCI is included in change in net unrealized gains/(losses) on securities AFS, net of tax.

[9] Amounts are generally included in mortgage production related income; however, the mark on certain fair value loans is included in other noninterest income

[10] Amounts are generally included in mortgage production related income; however, the mark on certain fair value loans is included in trading income.

[11] Amounts included in earnings are recognized in other noninterest expense

[12] Amounts included in earnings are recognized in other noninterest expense.