Shareholders' Equity - AOCI Activity (Details) $ in Millions	6 Months Ended
	Jun. 30, 2018 USD ($)
Accumulated Other Comprehensive Earnings (Loss)
Stockholders' Equity Attributable to Parent, Beginning Balance	$ 3,941
Stockholders' Equity Attributable to Parent, Ending Balance	3,889
Foreign Currency Translation
Accumulated Other Comprehensive Earnings (Loss)
Stockholders' Equity Attributable to Parent, Beginning Balance	(307)
Other comprehensive earnings (loss) before reclassifications	(111)
Stockholders' Equity Attributable to Parent, Ending Balance	(418)
Pension and Other Postretirement Benefits (Net of Tax)
Accumulated Other Comprehensive Earnings (Loss)
Stockholders' Equity Attributable to Parent, Beginning Balance	(362)
Amounts reclassified from accumulated other comprehensive earnings (loss)	14
Stockholders' Equity Attributable to Parent, Ending Balance	(348)
Effective Derivatives (Net of Tax)
Accumulated Other Comprehensive Earnings (Loss)
Stockholders' Equity Attributable to Parent, Beginning Balance	13
Other comprehensive earnings (loss) before reclassifications	34
Amounts reclassified from accumulated other comprehensive earnings (loss)	(48)
Stockholders' Equity Attributable to Parent, Ending Balance	(1)
Accumulated Other Comprehensive Earnings (Loss)
Accumulated Other Comprehensive Earnings (Loss)
Stockholders' Equity Attributable to Parent, Beginning Balance	(656)
Other comprehensive earnings (loss) before reclassifications	(77)
Amounts reclassified from accumulated other comprehensive earnings (loss)	(34)
Stockholders' Equity Attributable to Parent, Ending Balance	$ (767)