Affordable Housing Investments.

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Other collection items presented on behalf of custody clients.

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Federal Reserve And Foreign Central Bank Deposits

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Loan receivables that will be held to maturity.

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Standby Letters of Credit

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Amount of floating rate capital debt held by the company that have an unconditional obligation requiring the issuer to redeem the securities by transferring the assets at a specified or determinable date (or dates) or upon an event that is certain to occur. The debt was issued by a business trust to outside investors where the trust uses the proceeds of the issuance of those securities to purchase, from the financial institution that established the trust, an equivalent amount of junior subordinated debentures or other loans having stated maturities. The floating rate capital debt must be redeemed upon maturity of the debentures or other loans.

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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For banks and other depository institutions: Includes cash on hand (currency and coin), cash items in process of collection, noninterest bearing deposits due from other financial institutions (including corporate credit unions), and noninterest bearing balances with the Federal Reserve Banks, Federal Home Loan Banks and central banks.

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Fair value portion of arrangements with third parties, including, but not limited to, operating lease arrangement and arrangement in which the entity has agreed to expend funds to procure goods or services, or has agreed to commit resources to supply goods or services.

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Amount of short term borrowing where a bank borrows, at the federal funds rate, from another bank.

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Includes: (1) the amount outstanding of funds lent to other depository institutions, securities brokers, or securities dealers in the form of Federal Funds sold; for example, immediately available funds lent under agreements or contracts that mature in one business day or roll over under a continuing contract, regardless of the nature of the transaction or the collateral involved, excluding overnight lending for commercial and industrial purposes. Also include Federal Funds sold under agreements to resell on a gross basis, excluding (1) sales of term Federal Funds, (2) due bills representing purchases of securities or other assets by the reporting bank that have not yet been delivered and similar instruments, (3) resale agreements that mature in more than one business day involving assets other than securities, and (4) yield maintenance dollar repurchase agreements (Federal Funds Sold) and (2) the dollar amount outstanding of funds lent in the form of security resale agreements regardless of maturity, if the agreement requires the bank to resell the identical security purchased or a security that meets the definition of substantially the same in the case of a dollar roll. Also include purchases of participations in pools of securities, regardless of maturity (Securities Purchased Under Agreements to Re-sell).

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Amount of Federal Home Loan Bank (FHLB) and Federal Reserve Bank stock.

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Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

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Amount of foreign interest-bearing deposits held by the entity.

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For banks and other depository institutions (including Federal Reserve Banks, if applicable): Interest-bearing deposits in other financial institutions for relatively short periods of time including, for example, certificates of deposits, which are presented separately from cash on the balance sheet.

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Amount, after allowance for bad debt, of loan receivables held-for-sale that are not part of a disposal group. Excludes loans and leases covered under loss sharing agreements and loans classified as debt securities.

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The carrying amount as of the balance sheet date for the aggregate of other miscellaneous borrowings owed by the reporting entity.

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Amount, after the effects of master netting arrangements, of funds outstanding borrowed in the form of a security repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same securities at a date certain for a specified price. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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Carrying value as of the balance sheet date of collateralized/uncollateralized debt obligation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion. Subordinated debt places a lender in a lien position behind the primary lender of the company.

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Amount of time deposit liabilities, including certificates of deposit.

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Fair Value Measurements (Fair Value of Financial Instruments) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Assets
Cash and Due from Banks	$ 6,081.4	$ 4,518.1	$ 4,649.2	$ 5,332.0
Federal Reserve and Other Central Bank Deposits	29,446.8	40,479.1
Interest-Bearing Deposits with Banks	4,931.4	5,611.9
Federal Funds Sold and Securities Purchased under Agreements to Resell	1,534.0	1,324.3
Debt Securities
Available for Sale (Note)	34,258.0	33,742.1
Held to Maturity	14,334.6	13,049.0
Trading Account	8.9	0.5
Loans (excluding Leases)
Client Security Settlement Receivables	581.5	1,647.0
Deposits
Savings Certificates and Other Time	947.5	1,152.3
Non U.S. Offices Interest-Bearing	60,075.3	65,672.2
Federal Funds Purchased	332.8	2,286.1
Securities Sold Under Agreements to Repurchase	810.0	834.0
Other Borrowings	7,033.6	6,051.1
Senior Notes	1,497.5	1,497.3
Long Term Debt (excluding Leases)
Floating Rate Capital Debt	277.5	277.5
Derivative Instruments
Fair value asset	1,685.0	2,203.3
Fair value liability	1,652.2	2,003.1
Other Financial Derivatives
Derivative Instruments
Fair value asset	0.2
Fair value liability	31.3	30.4
Asset And Liability Management
Derivative Instruments
Fair value asset	79.6	60.9
Fair value liability	76.8	212.0
Client Related and Trading
Derivative Instruments
Fair value asset	2,059.0	2,592.1
Fair value liability	2,080.5	2,586.6
Client Related and Trading \| Foreign Exchange Contracts
Derivative Instruments
Fair value asset	1,995.8	2,527.0
Fair value liability	1,999.8	2,522.5
Client Related and Trading \| Interest Rate Contracts
Derivative Instruments
Fair value asset	63.2	65.1
Fair value liability	80.7	64.1
Level 2
Debt Securities
Available for Sale (Note)	28,600.0	28,000.0
Book Value
Assets
Cash and Due from Banks	6,081.4	4,518.1
Federal Reserve and Other Central Bank Deposits	29,446.8	40,479.1
Interest-Bearing Deposits with Banks	4,931.4	5,611.9
Federal Funds Sold and Securities Purchased under Agreements to Resell	1,534.0	1,324.3
Debt Securities
Available for Sale (Note)	34,258.0	33,742.1
Held to Maturity	14,334.6	13,049.0
Trading Account	8.9	0.5
Loans (excluding Leases)
Held for Investment	31,786.7	32,211.1
Held for Sale	0.8	20.9
Client Security Settlement Receivables	581.5	1,647.0
Other Assets
Federal Reserve and Federal Home Loan Bank Stock	268.1	223.1
Community Development Investments	405.5	415.3
Employee Benefit and Deferred Compensation	210.9	183.4
Deposits
Demand, Noninterest-Bearing, Savings, Money Market and Other Interest-Bearing	44,168.6	45,566.3
Savings Certificates and Other Time	947.5	1,152.3
Non U.S. Offices Interest-Bearing	60,075.3	65,672.2
Federal Funds Purchased	332.8	2,286.1
Securities Sold Under Agreements to Repurchase	810.0	834.0
Other Borrowings	7,033.6	6,051.1
Senior Notes	1,497.5	1,497.3
Long Term Debt (excluding Leases)
Subordinated Debt	1,410.0	1,435.1
Floating Rate Capital Debt	277.5	277.5
Other Liabilities
Standby Letters of Credit	29.4	30.3
Loan Commitments	32.1	33.1
Book Value \| Asset And Liability Management \| Foreign Exchange Contracts
Derivative Instruments
Fair value asset	56.8	30.1
Fair value liability	59.3	192.6
Book Value \| Asset And Liability Management \| Interest Rate Contracts
Derivative Instruments
Fair value asset	26.5	31.9
Fair value liability	18.0	19.4
Book Value \| Asset And Liability Management \| Other Financial Derivatives
Derivative Instruments
Fair value asset	0.2
Fair value liability	31.3	30.4
Book Value \| Client Related and Trading \| Foreign Exchange Contracts
Derivative Instruments
Fair value asset	1,995.8	2,527.0
Fair value liability	1,999.8	2,522.5
Book Value \| Client Related and Trading \| Interest Rate Contracts
Derivative Instruments
Fair value asset	63.2	65.1
Fair value liability	80.7	64.1
Total Fair Value
Assets
Cash and Due from Banks	6,081.4	4,518.1
Federal Reserve and Other Central Bank Deposits	29,446.8	40,479.1
Interest-Bearing Deposits with Banks	4,931.4	5,611.9
Federal Funds Sold and Securities Purchased under Agreements to Resell	1,534.0	1,324.3
Debt Securities
Available for Sale (Note)	34,258.0	33,742.1
Held to Maturity	14,260.4	13,010.9
Trading Account	8.9	0.5
Loans (excluding Leases)
Held for Investment	31,841.1	32,375.8
Held for Sale	0.8	20.9
Client Security Settlement Receivables	581.5	1,647.0
Other Assets
Federal Reserve and Federal Home Loan Bank Stock	268.1	223.1
Community Development Investments	405.5	415.3
Employee Benefit and Deferred Compensation	204.6	181.5
Deposits
Demand, Noninterest-Bearing, Savings, Money Market and Other Interest-Bearing	44,168.6	45,566.3
Savings Certificates and Other Time	947.4	1,153.6
Non U.S. Offices Interest-Bearing	60,075.3	65,672.2
Federal Funds Purchased	332.8	2,286.1
Securities Sold Under Agreements to Repurchase	810.0	834.0
Other Borrowings	7,035.2	6,052.9
Senior Notes	1,505.1	1,528.4
Long Term Debt (excluding Leases)
Subordinated Debt	1,412.6	1,449.8
Floating Rate Capital Debt	260.5	260.0
Other Liabilities
Standby Letters of Credit	29.4	30.3
Loan Commitments	32.1	33.1
Total Fair Value \| Asset And Liability Management \| Foreign Exchange Contracts
Derivative Instruments
Fair value asset	56.8	30.1
Fair value liability	59.3	192.6
Total Fair Value \| Asset And Liability Management \| Interest Rate Contracts
Derivative Instruments
Fair value asset	26.5	31.9
Fair value liability	18.0	19.4
Total Fair Value \| Asset And Liability Management \| Other Financial Derivatives
Derivative Instruments
Fair value asset	0.2
Fair value liability	31.3	30.4
Total Fair Value \| Client Related and Trading \| Foreign Exchange Contracts
Derivative Instruments
Fair value asset	1,995.8	2,527.0
Fair value liability	1,999.8	2,522.5
Total Fair Value \| Client Related and Trading \| Interest Rate Contracts
Derivative Instruments
Fair value asset	63.2	65.1
Fair value liability	80.7	64.1
Total Fair Value \| Level 1
Assets
Cash and Due from Banks	6,081.4	4,518.1
Debt Securities
Available for Sale (Note)	5,651.7	5,700.3
Held to Maturity	87.9	35.0
Other Assets
Employee Benefit and Deferred Compensation	132.3	115.5
Deposits
Demand, Noninterest-Bearing, Savings, Money Market and Other Interest-Bearing	44,168.6	45,566.3
Total Fair Value \| Level 2
Assets
Federal Reserve and Other Central Bank Deposits	29,446.8	40,479.1
Interest-Bearing Deposits with Banks	4,931.4	5,611.9
Federal Funds Sold and Securities Purchased under Agreements to Resell	1,534.0	1,324.3
Debt Securities
Available for Sale (Note)	28,603.4	28,037.5
Held to Maturity	14,172.5	12,975.9
Trading Account	8.9	0.5
Loans (excluding Leases)
Client Security Settlement Receivables	581.5	1,647.0
Other Assets
Federal Reserve and Federal Home Loan Bank Stock	268.1	223.1
Community Development Investments	405.5	415.3
Employee Benefit and Deferred Compensation	72.3	66.0
Deposits
Savings Certificates and Other Time	947.4	1,153.6
Non U.S. Offices Interest-Bearing	60,075.3	65,672.2
Federal Funds Purchased	332.8	2,286.1
Securities Sold Under Agreements to Repurchase	810.0	834.0
Other Borrowings	7,035.2	6,052.9
Senior Notes	1,505.1	1,528.4
Long Term Debt (excluding Leases)
Subordinated Debt	1,412.6	1,449.8
Floating Rate Capital Debt	260.5	260.0
Total Fair Value \| Level 2 \| Asset And Liability Management \| Foreign Exchange Contracts
Derivative Instruments
Fair value asset	56.8	30.1
Fair value liability	59.3	192.6
Total Fair Value \| Level 2 \| Asset And Liability Management \| Interest Rate Contracts
Derivative Instruments
Fair value asset	26.5	31.9
Fair value liability	18.0	19.4
Total Fair Value \| Level 2 \| Asset And Liability Management \| Other Financial Derivatives
Derivative Instruments
Fair value asset	0.2
Fair value liability	0.0	0.7
Total Fair Value \| Level 2 \| Client Related and Trading \| Foreign Exchange Contracts
Derivative Instruments
Fair value asset	1,995.8	2,527.0
Fair value liability	1,999.8	2,522.5
Total Fair Value \| Level 2 \| Client Related and Trading \| Interest Rate Contracts
Derivative Instruments
Fair value asset	63.2	65.1
Fair value liability	80.7	64.1
Total Fair Value \| Level 3
Debt Securities
Available for Sale (Note)	2.9	4.3
Loans (excluding Leases)
Held for Investment	31,841.1	32,375.8
Held for Sale	0.8	20.9
Other Liabilities
Standby Letters of Credit	29.4	30.3
Loan Commitments	32.1	33.1
Total Fair Value \| Level 3 \| Asset And Liability Management \| Other Financial Derivatives
Derivative Instruments
Fair value liability	$ 31.3	$ 29.7