Financial Instruments (Unaudited) Other Financial Instruments (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
Cash and Cash Equivalents [Line Items]
Credit Derivative, Maximum Exposure, Undiscounted	$ 226
Cash and cash equivalents	466	$ 464	$ 1,458	$ 1,985
Time Deposits [Member]
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 27	$ 48