Loans and Loans Held for Sale - Summary of Changes in Loans Held for Sale (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Loans Receivables [Abstract]
Balance at beginning of the period	$ 734us-gaap_LoansReceivableHeldForSaleNet	$ 784us-gaap_LoansReceivableHeldForSaleNet	$ 611us-gaap_LoansReceivableHeldForSaleNet
New originations	2,130	2,465	645
Transfers from (to) held to maturity, net	10	2	3
Loan sales	(1,204)	(2,516)	(596)
Loan draws (payments), net	(21)	(1)	(262)
Balance at end of period	$ 1,649us-gaap_LoansReceivableHeldForSaleNet	$ 734us-gaap_LoansReceivableHeldForSaleNet	$ 401us-gaap_LoansReceivableHeldForSaleNet

Net transfers from held to maturity.

No definition available.

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- Definition

Amount classified as loans attributable to disposal group held for sale or disposed of. Excludes loans and leases covered under loss sharing agreements and loans classified as debt securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 7

-Subparagraph a

-Article 9

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-Publisher FASB

-Name Accounting Standards Codification

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-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.7(a))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 948

-SubTopic 310

-Section 30

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- Definition

Reconcile the changes in loans that will be sold to other entities balances to the amounts presented in the consolidated statement of cash flows. Enter the additions to trade accounts that will be sold to other entities for the period.

+ References

+ Details

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- Definition

Reconcile the changes in loans that will be sold to other entities balances to the amounts presented in the consolidated statement of cash flows. Enter the deductions to trade accounts that will be sold to other entities for the period.

+ References

+ Details

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- Definition

The aggregate cash outflow used to purchase all loans that are held with the intention to resell in the near future.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

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