Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net sales and operating revenues	$ 2,372	$ 2,274	$ 7,483	$ 6,883
Cost of sales (exclusive of depreciation and amortization shown below)	2,014	1,911	6,371	5,789
Inventory	956		956		$ 864	$ 869
Prepayments and other (including contract assets)	369		369		297	291
Accrued liabilities	299		299			287
Retained earnings (accumulated deficit)	(823)		(823)		(947)	(946)
Increase in inventories	(65)	(56)	(118)	(116)
Increase in prepayments and other current assets	(21)	(8)	(91)	(76)
(Decrease) increase in other current liabilities	(19)	$ (51)	11	$ 101
Calculated under Revenue Guidance in Effect before Adjustments
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net sales and operating revenues	2,372		7,481
Cost of sales (exclusive of depreciation and amortization shown below)	2,014		6,369
Inventory	963		963			869
Prepayments and other (including contract assets)	349		349			291
Accrued liabilities	287		287
Retained earnings (accumulated deficit)	(824)		(824)			$ (946)
Increase in inventories	(64)		(125)
Increase in prepayments and other current assets	(21)		(71)
(Decrease) increase in other current liabilities	(20)		(1)
Adjustments due to ASU 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings (accumulated deficit)					1
Adjustments due to ASU 2014-09 | Difference between Revenue Guidance in Effect before and after Adjustments
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net sales and operating revenues	0		2
Cost of sales (exclusive of depreciation and amortization shown below)	0		2
Inventory	(7)		(7)		(5)
Prepayments and other (including contract assets)	20		20		6
Accrued liabilities	12		12
Retained earnings (accumulated deficit)	1		1
Increase in inventories	(1)		7
Increase in prepayments and other current assets	0		(20)
(Decrease) increase in other current liabilities	1		12
Adjustments due to ASU 2016-16 (a)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Inventory					0
Prepayments and other (including contract assets)					0
Retained earnings (accumulated deficit)					$ (2)
Transferred over Time
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue recognized	$ 1		$ 2