Basis of Financial Statements Adoption Adjustments (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2016
Item Effected [Line Items]
Net Cash Provided by (Used in) Financing Activities	$ (1,242)	$ (401)
Accounting Standards Update 2016-18 [Member]
Item Effected [Line Items]
Net Cash Provided by (Used in) Financing Activities		(247)
Restricted Cash		$ 32	$ 186