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Employee Incentive Plans (Share Grants And Fair Value) (Details) - USD ($) $ in Millions | 12 Months Ended | 92 Months Ended | 128 Months Ended
--- | --- | --- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2017
Employee Incentive Plans [Abstract] |  |  |  |  |  |
Shares granted | 923,407 | 1,451,136 | [1] | 1,211,533 | 20,888,468 |
Fair Value - Date of Grant | $ 55 | $ 55 |  | $ 52 | $ 397 | $ 55
Shares Granted IPO to Date |  |  |  |  |  | 24,474,544
Fair Value - Date of Grant IPO to Date |  |  |  |  |  | $ 559
[1] | Stock Incentive Plan number of granted restricted stock units related to 2016 was adjusted by 5,657 additional restricted stock units during the year ended December 31, 2017.Granted under the Company's amended 2007 Stock Incentive Plan, pending stockholder approval at the Company's 2018 Annual Meeting.

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- Definition Fair Value of all shares granted under the 2007 Stock Incentive Plan from the IPO to date. + References No definition available. + Details
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