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Derivatives and Hedging - Schedule of amounts of derivative gains (losses) recognized in the Consolidated Financial Statements (Details) - USD ($) $ in Millions | 3 Months Ended
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Mar. 31, 2018 | Mar. 31, 2017
Derivative [Line Items] |  |
Gain (Loss) Currently Recognized in Accumulated Other Comprehensive Loss | $ 14 | $ 6
Hedge gain (loss) to be reclassified during next twelve months | (2) |
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion) | (4) | 10
Compensation and benefits |  |
Derivative [Line Items] |  |
Hedge gain (loss) to be reclassified during next twelve months | 0 | 8
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion) | 1 | 13
Other General Expenses |  |
Derivative [Line Items] |  |
Hedge gain (loss) to be reclassified during next twelve months | 4 | 1
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion) | (1) | (1)
Interest expense |  |
Derivative [Line Items] |  |
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion) | (1) | 0
Other Income (Expense) |  |
Derivative [Line Items] |  |
Hedge gain (loss) to be reclassified during next twelve months | 10 | (3)
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion) | $ (3) | $ (2)

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- Definition Represents the estimated net amount of unrealized gains (losses) on hedges at the reporting date expected to be reclassified to earnings within the next 12 months. + References No definition available. + Details
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- Definition The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4D -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624177-113959 + Details
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- Definition The effective portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments that was recognized in other comprehensive income during the current period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959 + Details
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