Net Interest Revenue (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Interest revenue
Non-margin loans	$ 173	$ 178	$ 169
Margin loans	50bk_InterestAndFeeIncomeOnMarginLoans	48bk_InterestAndFeeIncomeOnMarginLoans	42bk_InterestAndFeeIncomeOnMarginLoans
Securities:
Taxable	439us-gaap_InterestIncomeSecuritiesTaxable	417us-gaap_InterestIncomeSecuritiesTaxable	405us-gaap_InterestIncomeSecuritiesTaxable
Exempt from federal income taxes	22	22	27
Total securities	461	439	432
Deposits with banks	30	30	73
Deposits with the Federal Reserve and other central banks	45	55	46
Federal funds sold and securities purchased under resale agreements	30	26	17
Trading assets	18	26	33
Total interest revenue	807	802	812
Interest expense
Deposits	15us-gaap_InterestExpenseDeposits	13us-gaap_InterestExpenseDeposits	22us-gaap_InterestExpenseDeposits
Federal funds purchased and securities sold under repurchase agreements	(3)	(2)	(4)
Trading liabilities	2	4	8
Other borrowed funds	2	2	1
Commercial paper	0us-gaap_InterestExpenseCommercialPaper	1us-gaap_InterestExpenseCommercialPaper	0us-gaap_InterestExpenseCommercialPaper
Customer payables	2bk_InterestExpenseCustomerPayables	3bk_InterestExpenseCustomerPayables	2bk_InterestExpenseCustomerPayables
Long-term debt	61us-gaap_InterestExpenseLongTermDebt	69us-gaap_InterestExpenseLongTermDebt	55us-gaap_InterestExpenseLongTermDebt
Total interest expense	79us-gaap_InterestExpense	90us-gaap_InterestExpense	84us-gaap_InterestExpense
Net interest revenue	$ 728us-gaap_InterestIncomeExpenseNet	$ 712us-gaap_InterestIncomeExpenseNet	$ 728us-gaap_InterestIncomeExpenseNet

Interest income from loans used to purchase shares of stock.

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Interest Expense Customer Payables

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Interest income derived from funds deposited with the Federal Reserve and other central banks.

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Represents the total of interest and dividend income, including any amortization and accretion (as applicable) of discounts and premiums, earned from (1) loans and leases whether held-for-sale or held-in-portfolio; (2) investment securities; (3) federal funds sold; (4) securities purchased under agreements to resell; (5) investments in banker's acceptances, commercial paper, or certificates of deposit; (6) dividend income; or (7) other investments not otherwise specified herein.

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Amount of operating dividend and interest income, including amortization and accretion of premiums and discounts, on securities.

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Amount of operating dividend and interest income, including amortization and accretion of premiums and discounts, on trading securities and other forms of securities that provide ownership interests.

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The aggregate interest and fee income generated by: (1) loans the Entity has positive intent and ability to hold for the foreseeable future, or until maturity or payoff, including commercial and consumer loans, whether domestic or foreign, which may consist of: (a) industrial and agricultural; (b) real estate; and (c) real estate construction loans; (d) trade financing; (e) lease financing; (f) home equity lines-of-credit; (g) automobile and other vehicle loans; and (h) credit card and other revolving-type loans and (2) loans and leases held-for-sale which may include mortgage loans, direct financing, and sales-type leases.

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Amount of the cost of borrowed funds accounted for as interest expense.

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Interest expense incurred during the reporting period on commercial paper.

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Aggregate amount of interest expense on all deposits.

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The aggregate expense incurred on federal funds purchased and securities sold under agreements to repurchase. If amounts recognized as payables under repurchase agreements have been offset against amounts recognized as receivables under reverse repurchase agreements and reported as a net amount on the balance sheet, the income and expense from these agreements may be reported on a net basis.

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Aggregate amount of interest paid or due on all long-term debt.

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Interest expense incurred during the reporting period on other short-term borrowings.

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Interest expense incurred on short positions arising from sales of securities and other assets, which the entity does not own, to other parties. Trading liabilities includes the fair value of derivative contracts held for trading that are in loss positions.

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Interest income derived from funds deposited with both domestic and foreign financial institutions including funds in money market and other accounts.

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The net amount of operating interest income (expense).

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The aggregate interest income earned from (1) the lending of excess federal funds to another commercial bank requiring such for its legal reserve requirements and (2) securities purchased under agreements to resell.

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Amount of operating interest income, including amortization and accretion of premiums and discounts, on securities subject to state, federal and other income tax.

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Amount of operating interest income, including amortization and accretion of premiums and discounts, on securities exempt from state, federal and other income tax.

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