Derivative Financial Instruments (Fair Value And Related Number Of Derivative Contracts Categorized By Predominant Risk Exposure) (Details) $ in Thousands	Sep. 30, 2016 USD ($) Contract	Dec. 31, 2015 USD ($) Contract
Derivatives, Fair Value [Line Items]
Fair Value, Assets	$ 6,243,274	$ 4,428,245
Fair Value, Liabilities	6,360,798	4,476,241
Counterparty/cash-collateral netting, Assets	(5,887,874)	(4,165,446)
Counterparty/cash-collateral netting, Liabilities	(5,970,029)	(4,257,998)
Total Derivative Assets per Consolidated Statement of Financial Condition	355,400	262,799
Total Derivative Liabilities per Consolidated Statement of Financial Condition	390,769	218,243
Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Assets	$ 4,873,516	$ 2,910,093
Number of Contracts, Assets \| Contract	31,728	56,748
Fair Value, Liabilities	$ 4,776,839	$ 2,849,958
Number of Contracts, Liabilities \| Contract	37,746	74,904
Foreign Exchange Contracts [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Assets	$ 428,868	$ 453,527
Number of Contracts, Assets \| Contract	9,997	8,089
Fair Value, Liabilities	$ 447,387	$ 466,021
Number of Contracts, Liabilities \| Contract	10,039	7,376
Fair value, increase in assets		$ (19,300)
Increase in number of contracts, assets \| Contract		(29)
Fair value, increase of liabilities		$ (4,600)
Increase in number of contracts, liabilities \| Contract		(28)
Equity Contracts [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Assets	$ 912,285	$ 1,017,611
Number of Contracts, Assets \| Contract	3,649,003	3,057,754
Fair Value, Liabilities	$ 1,094,330	$ 1,094,597
Number of Contracts, Liabilities \| Contract	3,184,904	2,947,416
Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Assets	$ 1,072	$ 27,590
Number of Contracts, Assets \| Contract	4,940	2,896
Fair Value, Liabilities	$ 1,489	$ 5,510
Number of Contracts, Liabilities \| Contract	1,741	2,001
Fair value, increase in assets		$ 19,300
Increase in number of contracts, assets \| Contract		29
Fair value, increase of liabilities		$ 4,600
Increase in number of contracts, liabilities \| Contract		28
Credit Contracts: Centrally Cleared Swaps [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Assets	$ 6,687	$ 2,447
Number of Contracts, Assets \| Contract	102	299
Fair Value, Liabilities	$ 8,710	$ 841
Number of Contracts, Liabilities \| Contract	41,889	44
Credit Contracts: Other Credit Derivatives [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Assets	$ 20,846	$ 16,977
Number of Contracts, Assets \| Contract	152	100
Fair Value, Liabilities	$ 32,043	$ 59,314
Number of Contracts, Liabilities \| Contract	189	135

Derivative Asset, Fair Value, Increase (Decrease) in Gross Asset

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Derivative Asset, Increase (Decrease) in Number of Instruments Held

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Derivative, Fair Value of Derivative Asset, Amount Netting in Consolidated Statement of Financial Condition

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Derivative, Fair Value of Derivative Liability, Amount Netting in Consolidated Statement of Financial Condition

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Derivative Liability, Fair Value, Increase (Decrease) of Gross Liability

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Derivative Liability, Increase (Decrease) in Number of Instruments Held

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The number of derivative instruments of a particular derivative asset or group of derivative assets held by the entity.

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Fair value, before 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 elected not to be offset. Excludes assets not subject to a master netting arrangement.

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Fair value, before 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 elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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The number of derivative instruments of a particular derivative liability or group of derivative liabilities held by the entity.

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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.

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The fair value as of the balance sheet date of firm holdings in all assets resulting from contracts that meet the criteria of being accounted for as derivative instruments. Their value is derived from the values of one or more underlying assets, reference rates, or indices of asset values. Includes both pledged (to counterparties as collateral for financing transactions) and unpledged holdings.

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Fair value of obligations arising from derivatives and other contracts sold short.

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