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Financial Assets And Financial Liabilities (Netting of Financial Assets) (Details) - USD ($) $ in Millions | Sep. 30, 2016 | Dec. 31, 2015
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Securities, Segregated For Regulatory Purposes, Purchased Under Agreements To Resell [Abstract] |  |  |
Gross Amounts of Financial Assets Recognized | [1] | $ 6,963 | $ 562
Amounts Offset in the Condensed Consolidated Statement of Financial Condition | [2] |  |
Net Amounts Presented in Condensed Consolidated Statement of Financial Condition |  | 6,963 | 562
Amounts Not Offset in the Condensed Consolidated Statement of Financial Condition: Cash or Financial Instruments |  | (6,963) | (562)
Offsetting Securities Borrowed [Abstract] |  |  |
Gross Amounts of Financial Assets Recognized |  | 4,785 | 3,924
Amounts Offset in the Condensed Consolidated Statement of Financial Condition |  |  |
Net Amounts Presented in Condensed Consolidated Statement of Financial Condition |  | 4,785 | 3,924
Amounts Not Offset in the Condensed Consolidated Statement of Financial Condition: Cash or Financial Instruments |  | (4,640) | (3,816)
Net Amount |  | 145 | 108
Offsetting Securities Purchased under Agreements to Resell [Abstract] |  |  |
Gross Amounts of Financial Assets Recognized |  | 148 | 195
Amounts Offset in the Condensed Consolidated Statement of Financial Condition |  |  |
Net Amounts Presented in Condensed Consolidated Statement of Financial Condition |  | 148 | 195
Amounts Not Offset in the Condensed Consolidated Statement of Financial Condition: Cash or Financial Instruments |  | (148) | (195)
Total [Abstract] |  |  |
Gross Amounts of Financial Assets Recognized |  | 13,536 | 5,921
Amounts Offset in the Condensed Consolidated Statement of Financial Condition |  |  |
Net Amounts Presented in Condensed Consolidated Statement of Financial Condition |  | 13,536 | 5,921
Amounts Not Offset in the Condensed Consolidated Statement of Financial Condition: Cash or Financial Instruments |  | (12,783) | (5,606)
Net Amount |  | 753 | 315
Options [Member] |  |  |
Offsetting Financial Instruments Owned, At Fair Value [Abstract] |  |  |
Gross Amounts of Financial Assets Recognized |  | 1,578 | 1,156
Amounts Offset in the Condensed Consolidated Statement of Financial Condition |  |  |
Net Amounts Presented in Condensed Consolidated Statement of Financial Condition |  | 1,578 | 1,156
Amounts Not Offset in the Condensed Consolidated Statement of Financial Condition: Cash or Financial Instruments |  | (1,031) | (1,032)
Net Amount |  | 547 | 124
Warrants And Discount Certificates [Member] |  |  |
Offsetting Financial Instruments Owned, At Fair Value [Abstract] |  |  |
Gross Amounts of Financial Assets Recognized |  | 57 | 81
Amounts Offset in the Condensed Consolidated Statement of Financial Condition |  |  |
Net Amounts Presented in Condensed Consolidated Statement of Financial Condition |  | 57 | 81
Amounts Not Offset in the Condensed Consolidated Statement of Financial Condition: Cash or Financial Instruments |  | (1) | (1)
Net Amount |  | 56 | 80
Currency Forward Contracts [Member] |  |  |
Offsetting Financial Instruments Owned, At Fair Value [Abstract] |  |  |
Gross Amounts of Financial Assets Recognized |  | 5 | 3
Amounts Offset in the Condensed Consolidated Statement of Financial Condition |  |  |
Net Amounts Presented in Condensed Consolidated Statement of Financial Condition |  | 5 | 3
Net Amount |  | $ 5 | $ 3
[1] | As of September 30, 2016 and December 31, 2015, the Company had $7.0 billion and $0.6 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 September 30, 2016 and December 31, 2015.

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