Income Taxes (Details 5) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities		$ (84)	$ 0	$ (14)
Decrease In Unrecognized Tax Benefits is Reasonably Possible		(70)
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued		7
Unrecognized Tax Benefits that Would Impact Effective Tax Rate		112
Tax Credit Carryforward, Amount		18
Operating Loss Carryforwards		191
Undistributed Earnings of Foreign Subsidiaries		70
Foreign Earnings Repatriated		352
Deferred Tax Assets, Gross [Abstract]
Valuation allowance against tax assets		31	$ 34
Maximum | Forecast
Income Tax Contingency [Line Items]
Tax Adjustments, Settlements, and Unusual Provisions	$ 40
Resolution of IRS examination of the company's 2007-2011 tax returns [Member]
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities		$ (115)