Fair Values of Assets and Liabilities (Significant Unobservable Level 3 Inputs Nonrecurring Basis) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Commercial Loans Held For Sale
Fair Value Inputs [Line Items]
Fair value measurements nonrecurring assets	1
Commercial and Industrial Loans
Fair Value Inputs [Line Items]
Fair value measurements nonrecurring assets	366	22
Commercial Mortgage Loans
Fair Value Inputs [Line Items]
Fair value measurements nonrecurring assets	52	31
Commercial Construction Loans
Fair Value Inputs [Line Items]
Fair value measurements nonrecurring assets		2
Residential mortgage loans
Fair Value Inputs [Line Items]
Fair value measurements nonrecurring assets	55
Servicing Rights
Fair Value Inputs [Line Items]
Fair value measurements nonrecurring assets	788	972
OREO Property
Fair Value Inputs [Line Items]
Fair value measurements nonrecurring assets	36	95
Bank premises and equipment
Fair Value Inputs [Line Items]
Fair value measurements nonrecurring assets	5
Operating lease equipment
Fair Value Inputs [Line Items]
Fair value measurements nonrecurring assets	39
Minimum \| Servicing Rights
Fair Value Inputs [Line Items]
Prepayment speed	0.60%	0.00%
Discount rate		9.60%
OAS spread (bps)	430
Maximum \| Servicing Rights
Fair Value Inputs [Line Items]
Prepayment speed	100.00%	100.00%
Discount rate		13.20%
OAS spread (bps)	1700
Weighted average \| Commercial Loans Held For Sale
Fair Value Inputs [Line Items]
Cost to sell	10.00%
Weighted average \| Fixed \| Servicing Rights
Fair Value Inputs [Line Items]
Prepayment speed	10.00%	10.60%
Discount rate		9.90%
OAS spread (bps)	920
Weighted average \| Adjustable \| Servicing Rights
Fair Value Inputs [Line Items]
Prepayment speed	32.20%	26.10%
Discount rate		11.80%
OAS spread (bps)	640

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- Definition

No authoritative reference available.

+ References

No definition available.

+ Details

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- Definition

The OAS represents the spread that is added to the discount rate so that the sum of the discounted cash flows equals the market price; therefore, it is a measure of the extra yield over the reference discount factor that the Corporation expects to earn by holding the asset.

+ References

No definition available.

+ Details

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- Definition

Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (bbb)

-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

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- Definition

Rate at which loans or a loan portfolio are expected to prepay principal balances, used as an input to measure fair value.

+ References

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