Balance Sheet Offsetting (Details) - Foreign Exchange Contract [Member] - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Assets
Gross Amounts Recognized	$ 140	$ 813
Gross Amount Offset in the Consolidated Balance Sheet	0	0
Net Amounts Presented in the Consolidated Balance Sheet	140	813
Gross Amounts Not Offset in the Consolidated Balance Sheet - Financial Instruments	(50)	(126)
Gross Amounts Not Offset in the Consolidated Balance Sheet - Cash Collateral Received/Pledged	(78)	(607)
Net Amount	12	80
Liabilities
Gross Amounts Recognized	1,128	163
Gross Amount Offset in the Consolidated Balance Sheet	0	0
Net Amounts Presented in the Consolidated Balance Sheet	1,128	163
Gross Amounts Not Offset in the Consolidated Balance Sheet - Financial Instruments	(50)	(126)
Gross Amounts Not Offset in the Consolidated Balance Sheet - Cash Collateral Received/Pledged	(1,004)	(31)
Net Amount	$ 74	$ 6

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