Revision of Previously Issued Financial Statements (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		15 Months Ended	48 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Mar. 31, 2017	Mar. 31, 2017
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Increase (decrease) in accrued taxes	$ 16	$ 0	$ (22)	$ 9
Cost of sales	1,913	1,743	5,790	5,329
Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Increase (decrease) in accrued taxes		(1)		(1)
Cost of sales		2		8
As Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Increase (decrease) in accrued taxes		1		10
Cost of sales		$ 1,741		$ 5,321
Lump Sum Payments Immediately Recognized, Should Have Been Deferred And Amortized | Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Cost of sales						$ 34
Deferred charges	$ 25		$ 25
AccrualsForSubstrateLiabilitiesAndAssociatedCostOfSales [Member] | Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Cost of sales					$ 7