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, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014		Dec. 31, 2014	Dec. 31, 2013
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	(3)		(2)
Settlements	0		0
Transfers to other balance sheet line items	0		4
Transfers into Level 3	6		5
Transferred Out of Level 3 in The Fair Value Hierarchy	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	4		2		1	3
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income	0		0
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			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			11	[1]
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			54
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income			0
Trading Assets [Member]
Included in earnings			72
OCI			0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases			0
Sales			(72)
Settlements			(1)
Transfers to other balance sheet line items			55
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			11			65
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	77	[2]	60	[2]
OCI	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	0		0
Sales	0		0
Settlements	0		1
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	37		11		20	5
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income	(4)	[2],[3]	0
Available-for-sale Securities [Member]
Included in earnings	0		(2)	[4]
OCI	1	[5]	4	[6]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	21		0
Sales	0		(20)
Settlements	(201)		(35)
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	767		900		946	953
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		(2)
OCI	0		1
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	0		0
Sales	0		(20)
Settlements	(6)		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	6		13		12	34
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	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	21		21		21	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	21		0
Sales	0		0
Settlements	(190)		(27)
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	616		712		785	739
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		3
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	0		0
Sales	0		0
Settlements	(5)		(8)
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	119		149		123	154
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	[7]	4	[8]
OCI	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	0		0
Sales	0		0
Settlements	(9)		(11)
Transfers to other balance sheet line items	0		(4)
Transfers into Level 3	2		0
Transferred Out of Level 3 in The Fair Value Hierarchy	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	268		299		272	302
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income	2	[3],[7]	3	[8],[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	(10)		0
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	21		26		27	26
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings	4	[10]	0
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	(60)		(55)
Interest Rate Lock Commitments [Member] | Trading Assets [Member] | Derivative contracts, net [Member]
Transfers to other balance sheet line items	$ 60		$ 55

[1] 3 Amounts included in earnings are recognized in trading income.

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

[3] 1 Change in unrealized gains/(losses) included in earnings during the period related to financial assets still held at March 31, 2015.

[4] 4 Amounts included in earnings are recognized in net securities losses.

[5] 3 Amount recognized in OCI is included in change in net unrealized gains on securities AFS, net of tax.

[6] 5 Amounts recognized in OCI are included in change in net unrealized gains on securities AFS, net of tax.

[7] 4 Amounts are generally included in mortgage production related income; however, the mark on certain fair value loans is included in trading income.

[8] 6 Amounts are generally included in mortgage production related income; however, the mark on certain fair value loans is included in trading income.

[9] 1 Change in unrealized gains/(losses) included in earnings for the period related to financial assets still held at March 31, 2014.

[10] 5 Amounts included in earnings are recognized in other noninterest expense.