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
		Mar. 31, 2016		Mar. 31, 2015		Dec. 31, 2015	Dec. 31, 2014
Loans Held For Sale [Member] | Residential Mortgage, Loans Held For Sale [Member]
Included in earnings		$ 0		$ 0
OCI		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0		0
Sales		(7)		(3)
Settlements		0		0
Transfers to other balance sheet line items		(1)		0
Transfers into Level 3		9		6
Transferred Out of Level 3 in The Fair Value Hierarchy		(2)		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		4		4		$ 5	$ 1
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income		0		0
Trading Account Assets [Member]
Included in earnings		44
OCI		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0
Sales		(88)
Settlements		1
Transfers to other balance sheet line items		(29)
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		32				104
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income		36
Trading Account Assets [Member] | Collateralized Debt Obligations [Member]
Included in earnings	[1]	(1)
OCI		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0
Sales		(88)
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				89
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		45	[2]	77	[3]
OCI		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0		0
Sales		0		0
Settlements		1		0
Transfers into Level 3		0		0
Transferred Out of Level 3 in The Fair Value Hierarchy		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		32		37		15	20
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income		36	[2],[4]	41	[3],[5]
Available-for-sale Securities [Member]
Included in earnings		0		0
OCI		(1)	[6]	1	[7]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		106		21
Sales		0		0
Settlements		81		201
Transfers to other balance sheet line items		0		0
Transfers into Level 3		0		0
Transferred Out of Level 3 in The Fair Value Hierarchy		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		580		767		556	946
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income		0		0
Available-for-sale Securities [Member] | US States and Political Subdivisions Debt Securities [Member]
Included in earnings		0		0
OCI		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0		0
Sales		0		0
Settlements		0		6
Transfers to other balance sheet line items		0		0
Transfers into Level 3		0		0
Transferred Out of Level 3 in The Fair Value Hierarchy		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		5		6		5	12
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income		0		0
Available-for-sale Securities [Member] | Asset-backed Securities [Member]
Included in earnings		0		0
OCI		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0		0
Sales		0		0
Settlements		1		0
Transfers to other balance sheet line items		0		0
Transfers into Level 3		0		0
Transferred Out of Level 3 in The Fair Value Hierarchy		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		11		21		12	21
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income		0		0
Available-for-sale Securities [Member] | Other Debt Obligations [Member]
Included in earnings		0		0
OCI		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0		0
Sales		0		0
Settlements		0		0
Transfers to other balance sheet line items		0		0
Transfers into Level 3		0		0
Transferred Out of Level 3 in The Fair Value Hierarchy		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		5		5		5	5
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income		0		0
Available-for-sale Securities [Member] | Equity Securities [Member]
Included in earnings		0		0
OCI		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		106		21
Sales		0		0
Settlements		75		190
Transfers to other balance sheet line items		0		0
Transfers into Level 3		0		0
Transferred Out of Level 3 in The Fair Value Hierarchy		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		471		616		440	785
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income		0		0
Available-for-sale Securities [Member] | Mortgage-backed Securities, Issued by Private Enterprises [Member]
Included in earnings		0		0
OCI		(1)	[6]	1	[7]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0		0
Sales		0		0
Settlements		5		5
Transfers to other balance sheet line items		0		0
Transfers into Level 3		0		0
Transferred Out of Level 3 in The Fair Value Hierarchy		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		88		119		94	123
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income		0		0
Loans Held For Investment [Member]
Included in earnings		3	[8]	3	[9]
OCI		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0		0
Sales		0		0
Settlements		10		9
Transfers to other balance sheet line items		1		0
Transfers into Level 3		4		2
Transferred Out of Level 3 in The Fair Value Hierarchy		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		255		268		257	272
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income		3	[4],[8]	2	[5],[9]
Other Liabilities [Member]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Sales		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements		(23)		(10)
Transfers to other balance sheet line items		0		0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Liabilities Transfers Into Level 3		0		0
Fair Value Measurement With Unobservable Inputs Reconciliation, Recurring Basis, Liabilities Transfers Out Of Level 3		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		0
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value		0		21		$ 23	$ 27
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings		0		4	[10]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Other Comprehensive Income (Loss)		0		0
Interest Rate Lock Commitments [Member]
Transferred Out of Level 3 in The Fair Value Hierarchy		(29)		(60)
Interest Rate Lock Commitments [Member] | Trading Assets [Member] | Derivative contracts, net [Member]
Transfers to other balance sheet line items		$ (29)		$ (60)

[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 March 31, 2016

[5] Change in unrealized gains/(losses) included in earnings for the period related to financial assets still held at March 31, 2015

[6] Amount recognized in OCI is included in change in net unrealized gains on securities AFS, net of tax.

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

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

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

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