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Financial Assets And Financial Liabilities (Netting of Financial Assets) (Details) - USD ($) $ in Millions | Jun. 30, 2017 | Dec. 31, 2016
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Securities, Segregated For Regulatory Purposes, Purchased Under Agreements To Resell [Abstract] |  |  |
Gross Amounts of Financial Assets Recognized | [1] | $ 13,774 | $ 10,995
Amounts Offset in the Condensed Consolidated Statement of Financial Condition | [2] |  |
Net Amounts Presented in Condensed Consolidated Statement of Financial Condition |  | 13,774 | 10,995
Amounts Not Offset in the Condensed Consolidated Statement of Financial Condition: Cash or Financial Instruments |  | (13,774) | (10,995)
Offsetting Securities Borrowed [Abstract] |  |  |
Gross Amounts of Financial Assets Recognized |  | 3,895 | 3,629
Amounts Offset in the Condensed Consolidated Statement of Financial Condition | [2] |  |
Net Amounts Presented in Condensed Consolidated Statement of Financial Condition |  | 3,895 | 3,629
Amounts Not Offset in the Condensed Consolidated Statement of Financial Condition: Cash or Financial Instruments |  | (3,750) | (3,488)
Net Amount |  | 145 | 141
Offsetting Securities Purchased under Agreements to Resell [Abstract] |  |  |
Gross Amounts of Financial Assets Recognized |  | 366 | 111
Amounts Offset in the Condensed Consolidated Statement of Financial Condition | [2] |  |
Net Amounts Presented in Condensed Consolidated Statement of Financial Condition |  | 366 | 111
Amounts Not Offset in the Condensed Consolidated Statement of Financial Condition: Cash or Financial Instruments |  | (366) | (111)
Total [Abstract] |  |  |
Gross Amounts of Financial Assets Recognized |  | 19,036 | 16,585
Amounts Offset in the Condensed Consolidated Statement of Financial Condition | [2] |  |
Net Amounts Presented in Condensed Consolidated Statement of Financial Condition |  | 19,036 | 16,585
Amounts Not Offset in the Condensed Consolidated Statement of Financial Condition: Cash or Financial Instruments |  | (18,235) | (15,825)
Net Amount |  | 801 | 760
Options [Member] |  |  |
Offsetting Financial Instruments Owned, At Fair Value [Abstract] |  |  |
Gross Amounts of Financial Assets Recognized |  | 973 | 1,804
Amounts Offset in the Condensed Consolidated Statement of Financial Condition | [2] |  |
Net Amounts Presented in Condensed Consolidated Statement of Financial Condition |  | 973 | 1,804
Amounts Not Offset in the Condensed Consolidated Statement of Financial Condition: Cash or Financial Instruments |  | (345) | (1,230)
Net Amount |  | 628 | 574
Warrants And Discount Certificates [Member] |  |  |
Offsetting Financial Instruments Owned, At Fair Value [Abstract] |  |  |
Gross Amounts of Financial Assets Recognized |  | 3 | 43
Amounts Offset in the Condensed Consolidated Statement of Financial Condition | [2] |  |
Net Amounts Presented in Condensed Consolidated Statement of Financial Condition |  | 3 | 43
Amounts Not Offset in the Condensed Consolidated Statement of Financial Condition: Cash or Financial Instruments |  |  | (1)
Net Amount |  | 3 | 42
Currency Forward Contracts [Member] |  |  |
Offsetting Financial Instruments Owned, At Fair Value [Abstract] |  |  |
Gross Amounts of Financial Assets Recognized |  | 25 | 3
Amounts Offset in the Condensed Consolidated Statement of Financial Condition | [2] |  |
Net Amounts Presented in Condensed Consolidated Statement of Financial Condition |  | 25 | 3
Net Amount |  | $ 25 | $ 3
[1] | As of June 30, 2017 and December 31, 2016, the Company had $13.8 billion and $11.0 billion, respectively, of securities purchased under agreements to resell that were segregated to satisfy regulatory requirements. These securities are included in "Cash and securities - segregated for regulatory purposes" in the condensed consolidated statements of financial condition.
[2] | The Company did not have any balances eligible for netting in accordance with ASC Topic 210-20 at June 30, 2017 and December 31, 2016.

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