Background (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income tax expense	$ 144	$ 144
Operating income	631	688
Total other expense, net	(324)	(308)
Restatement adjustment | Accounting Standards Update 2016-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income tax expense	7
Accounting Standards Update 2016-09 | Restatement adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect on retained earnings, net of tax	3
Cumulative effect on retained earnings, tax	$ 2
Accounting Standards Update 2017-07 | Restatement adjustment | New accounting pronouncement, early adoption, effect
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating income		(6)
Total other expense, net		$ 6