Accounting Policies (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash provided by (used in) operating activities	$ (286)	$ (372)
Net cash provided by (used in) financing activities	398	204
Cash and Cash Equivalents	961	1,079	$ 1,132
Restricted Cash	90	19	57
Total Cash, Cash Equivalents, and Restricted Cash	$ 1,051	1,098	$ 1,189	$ 1,502
Accounting Standards Update 2016-15 | New Accounting Pronouncement, Early Adoption, Effect
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash provided by (used in) operating activities		(9)
Net cash provided by (used in) financing activities		$ 9