Fair Value Measurements - Carrying Value and Estimated Fair Value of Financial Instruments (Detail) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
Fair Value Of Other Financial Instrument [Line Items]
Derivatives	$ 3,927	$ 5,614
Loans and Leases Receivable, Net Amount	76,565	82,005	$ 84,264
Derivatives	6,897	6,993
Level 1 [Member]
Fair Value Of Other Financial Instrument [Line Items]
Short-term financial assets	903	968
Federal Funds Sold and Securities Purchased under Agreements to Resell	0	0
Securities Purchased under Agreements to Resell, Fair Value Option	0
Non-derivative trading assets	4,374	3,088
Derivatives	5	5
Securities	26,435	21,924
Short-term financial liabilities	0	0
Deposits designated under fair value option	0	0
Non-derivative trading liabilities	1,030	363
Derivatives	8	9
Short-term borrowings designated under fair value option	0	0
Long-term debt	0	0
Long-term debt designated under fair value option	0	0
Level 1 [Member] \| Commercial Loans [Member]
Fair Value Of Other Financial Instrument [Line Items]
Commercial loans designated under fair value option and held for sale	0	0
Loans held for sale	0	0
Level 1 [Member] \| Consumer Loans [Member] \| Residential mortgages and home equity mortgages [Member]
Fair Value Of Other Financial Instrument [Line Items]
Loans held for sale	0	0
Level 1 [Member] \| Consumer Loans [Member] \| Other consumer [Member]
Fair Value Of Other Financial Instrument [Line Items]
Loans held for sale	0	0
Level 1 [Member] \| Deposits Without Fixed Maturities [Member]
Fair Value Of Other Financial Instrument [Line Items]
Deposits	0	0
Level 1 [Member] \| Deposits With Fixed Maturities [Member]
Fair Value Of Other Financial Instrument [Line Items]
Deposits	0	0
Level 2 [Member]
Fair Value Of Other Financial Instrument [Line Items]
Short-term financial assets	17,139	7,478
Federal Funds Sold and Securities Purchased under Agreements to Resell	29,945	19,847
Securities Purchased under Agreements to Resell, Fair Value Option	769
Non-derivative trading assets	8,463	5,756
Derivatives	3,904	5,579
Securities	28,127	28,014
Short-term financial liabilities	3,449	3,076
Deposits designated under fair value option	6,068	5,052
Non-derivative trading liabilities	49	686
Derivatives	6,877	6,957
Short-term borrowings designated under fair value option	2,675	1,976
Long-term debt	30,442	24,874
Long-term debt designated under fair value option	9,486	8,425
Level 2 [Member] \| Commercial Loans [Member]
Fair Value Of Other Financial Instrument [Line Items]
Commercial loans designated under fair value option and held for sale	649	151
Loans held for sale	92	55
Level 2 [Member] \| Consumer Loans [Member] \| Residential mortgages and home equity mortgages [Member]
Fair Value Of Other Financial Instrument [Line Items]
Loans held for sale	18	7
Level 2 [Member] \| Consumer Loans [Member] \| Other consumer [Member]
Fair Value Of Other Financial Instrument [Line Items]
Loans held for sale	0	0
Level 2 [Member] \| Deposits Without Fixed Maturities [Member]
Fair Value Of Other Financial Instrument [Line Items]
Deposits	112,211	101,146
Level 2 [Member] \| Deposits With Fixed Maturities [Member]
Fair Value Of Other Financial Instrument [Line Items]
Deposits	11,434	10,508
Level 3 [Member]
Fair Value Of Other Financial Instrument [Line Items]
Short-term financial assets	20	48
Federal Funds Sold and Securities Purchased under Agreements to Resell	0	0
Securities Purchased under Agreements to Resell, Fair Value Option	0
Non-derivative trading assets	3,075	3,091
Derivatives	18	30
Securities	0	0
Short-term financial liabilities	20	48
Deposits designated under fair value option	1,404	1,867
Non-derivative trading liabilities	0	0
Derivatives	12	27
Short-term borrowings designated under fair value option	0	0
Long-term debt	0	0
Long-term debt designated under fair value option	513	746
Level 3 [Member] \| Commercial Loans [Member]
Fair Value Of Other Financial Instrument [Line Items]
Commercial loans designated under fair value option and held for sale	0	0
Loans held for sale	0	1,903
Level 3 [Member] \| Consumer Loans [Member] \| Residential mortgages and home equity mortgages [Member]
Fair Value Of Other Financial Instrument [Line Items]
Loans held for sale	954	4
Level 3 [Member] \| Consumer Loans [Member] \| Other consumer [Member]
Fair Value Of Other Financial Instrument [Line Items]
Loans held for sale	75	79
Level 3 [Member] \| Deposits Without Fixed Maturities [Member]
Fair Value Of Other Financial Instrument [Line Items]
Deposits	0	0
Level 3 [Member] \| Deposits With Fixed Maturities [Member]
Fair Value Of Other Financial Instrument [Line Items]
Deposits	0	0
Carrying Value [Member]
Fair Value Of Other Financial Instrument [Line Items]
Short-term financial assets	18,062	8,494
Federal Funds Sold and Securities Purchased under Agreements to Resell	29,945	19,847
Securities Purchased under Agreements to Resell, Fair Value Option	769
Non-derivative trading assets	15,912	11,935
Derivatives	3,927	5,614
Securities	54,231	49,797
Short-term financial liabilities	3,407	3,082
Deposits designated under fair value option	7,472	6,919
Non-derivative trading liabilities	1,079	1,049
Derivatives	6,897	6,993
Short-term borrowings designated under fair value option	2,675	1,976
Long-term debt	29,501	24,338
Long-term debt designated under fair value option	9,999	9,171
Carrying Value [Member] \| Commercial Loans [Member]
Fair Value Of Other Financial Instrument [Line Items]
Commercial loans designated under fair value option and held for sale	649	151
Loans held for sale	92	1,944
Carrying Value [Member] \| Consumer Loans [Member] \| Residential mortgages and home equity mortgages [Member]
Fair Value Of Other Financial Instrument [Line Items]
Loans held for sale	971	11
Carrying Value [Member] \| Consumer Loans [Member] \| Other consumer [Member]
Fair Value Of Other Financial Instrument [Line Items]
Loans held for sale	75	79
Carrying Value [Member] \| Deposits Without Fixed Maturities [Member]
Fair Value Of Other Financial Instrument [Line Items]
Deposits	112,211	101,146
Carrying Value [Member] \| Deposits With Fixed Maturities [Member]
Fair Value Of Other Financial Instrument [Line Items]
Deposits	11,399	10,514
Estimate of fair value [Member]
Fair Value Of Other Financial Instrument [Line Items]
Short-term financial assets	18,062	8,494
Federal Funds Sold and Securities Purchased under Agreements to Resell	29,945	19,847
Securities Purchased under Agreements to Resell, Fair Value Option	769
Non-derivative trading assets	15,912	11,935
Derivatives	3,927	5,614
Securities	54,562	49,938
Short-term financial liabilities	3,469	3,124
Deposits designated under fair value option	7,472	6,919
Non-derivative trading liabilities	1,079	1,049
Derivatives	6,897	6,993
Short-term borrowings designated under fair value option	2,675	1,976
Long-term debt	30,442	24,874
Long-term debt designated under fair value option	9,999	9,171
Estimate of fair value [Member] \| Commercial Loans [Member]
Fair Value Of Other Financial Instrument [Line Items]
Commercial loans designated under fair value option and held for sale	649	151
Loans held for sale	92	1,958
Estimate of fair value [Member] \| Consumer Loans [Member] \| Residential mortgages and home equity mortgages [Member]
Fair Value Of Other Financial Instrument [Line Items]
Loans held for sale	972	11
Estimate of fair value [Member] \| Consumer Loans [Member] \| Other consumer [Member]
Fair Value Of Other Financial Instrument [Line Items]
Loans held for sale	75	79
Estimate of fair value [Member] \| Deposits Without Fixed Maturities [Member]
Fair Value Of Other Financial Instrument [Line Items]
Deposits	112,211	101,146
Estimate of fair value [Member] \| Deposits With Fixed Maturities [Member]
Fair Value Of Other Financial Instrument [Line Items]
Deposits	11,434	10,508
Commercial Portfolio Segment [Member] \| Level 1 [Member]
Fair Value Of Other Financial Instrument [Line Items]
Loans and Leases Receivable, Net Amount	0	0
Commercial Portfolio Segment [Member] \| Level 2 [Member]
Fair Value Of Other Financial Instrument [Line Items]
Loans and Leases Receivable, Net Amount	0	0
Commercial Portfolio Segment [Member] \| Level 3 [Member]
Fair Value Of Other Financial Instrument [Line Items]
Loans and Leases Receivable, Net Amount	58,676	62,417
Commercial Portfolio Segment [Member] \| Carrying Value [Member]
Fair Value Of Other Financial Instrument [Line Items]
Loans and Leases Receivable, Net Amount	57,061	61,674
Commercial Portfolio Segment [Member] \| Estimate of fair value [Member]
Fair Value Of Other Financial Instrument [Line Items]
Loans and Leases Receivable, Net Amount	58,676	62,417
Other consumer [Member] \| Level 1 [Member]
Fair Value Of Other Financial Instrument [Line Items]
Loans and Leases Receivable, Net Amount	0	0
Other consumer [Member] \| Level 2 [Member]
Fair Value Of Other Financial Instrument [Line Items]
Loans and Leases Receivable, Net Amount	0	0
Other consumer [Member] \| Level 3 [Member]
Fair Value Of Other Financial Instrument [Line Items]
Loans and Leases Receivable, Net Amount	18,753	19,185
Other consumer [Member] \| Carrying Value [Member]
Fair Value Of Other Financial Instrument [Line Items]
Loans and Leases Receivable, Net Amount	19,504	20,331
Other consumer [Member] \| Estimate of fair value [Member]
Fair Value Of Other Financial Instrument [Line Items]
Loans and Leases Receivable, Net Amount	$ 18,753	$ 19,185

Fair Value of Commercial Syndicated Loans Held For Sale

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- Definition

Interest bearing deposits domestic fair value option disclosure.

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This element represents the portion of long term debt that the entity has elected to value at fair value under the fair value option.

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Non-derivative trading assets fair value disclosure.

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Non derivative trading liability.

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Securities, Fair Value Disclosure

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Securities Purchased under Agreements to Resell, Fair Value Option

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No definition available.

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- Definition

Short-term financial assets fair value disclosure.

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- Definition

Short-term Financial Liabilities, Fair Value

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No definition available.

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- Definition

Fair value portion of deposit liabilities held by the entity, including, but not limited to, foreign and domestic, interest and noninterest bearing, demand deposits, saving deposits, negotiable orders of withdrawal (NOW) and time deposits.

+ References

No definition available.

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- Definition

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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- Definition

Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Fair value portion of federal funds sold and securities borrowed or purchased under agreements to resell.

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- Definition

Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

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- Definition

Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

+ References

No definition available.

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- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

+ Details

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- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents the amount of short-term debt existing as of the balance sheet date.

+ References

No definition available.

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