Summary of Accounting Policies - Adoption of ASC 606 (Details) - USD ($)		3 Months Ended										12 Months Ended
		Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018		Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017		Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016	Jan. 01, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Inventories		$ 2,245,000,000					$ 820,000,000					$ 2,245,000,000		$ 820,000,000
Prepayments and other current assets		590,000,000					288,000,000					590,000,000		288,000,000
Accrued expenses and other current liabilities		1,001,000,000										1,001,000,000
Accumulated deficit		(1,013,000,000)					(1,009,000,000)					(1,013,000,000)		(1,009,000,000)
Net sales and operating revenues		4,278,000,000	$ 2,371,000,000	$ 2,533,000,000	$ 2,581,000,000		2,389,000,000	$ 2,273,000,000	$ 2,314,000,000	$ 2,298,000,000		11,763,000,000		9,274,000,000		$ 8,597,000,000
Cost of sales (exclusive of depreciation and amortization)		3,698,000,000	2,014,000,000	2,157,000,000	2,202,000,000		2,019,000,000	1,912,000,000	1,949,000,000	1,932,000,000		10,071,000,000		7,812,000,000		7,126,000,000
Selling, general, and administrative												794,000,000		638,000,000		514,000,000
Non-service pension and postretirement benefit costs												20,000,000		16,000,000		84,000,000
Other expense (income), net												12,000,000		(2,000,000)		(1,000,000)
Receivables												(190,000,000)		(81,000,000)		(325,000,000)
Net cash provided by operating activities												439,000,000		517,000,000		374,000,000
Change in restricted cash														0		0
Proceeds from deferred purchase price of factored receivables												174,000,000		112,000,000		110,000,000
Net cash used by investing activities												(2,514,000,000)		(300,000,000)		(229,000,000)
Increase (decrease) in cash, cash equivalents and restricted cash												384,000,000		(31,000,000)		61,000,000
Cash, cash equivalents and restricted cash, January 1					318,000,000	[1]				349,000,000	[1]	318,000,000	[1]	349,000,000	[1]	288,000,000
Cash, cash equivalents and restricted cash, December 31	[1]	702,000,000					318,000,000					702,000,000		318,000,000		349,000,000
As Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Inventories							869,000,000							869,000,000
Prepayments and other current assets							291,000,000							291,000,000
Accumulated deficit							(946,000,000)							(946,000,000)
Net sales and operating revenues			2,372,000,000	2,537,000,000	2,574,000,000		2,391,000,000	2,274,000,000	2,317,000,000	2,292,000,000				9,274,000,000		8,599,000,000
Cost of sales (exclusive of depreciation and amortization)			$ 2,014,000,000	$ 2,159,000,000	2,198,000,000		2,020,000,000	$ 1,911,000,000	$ 1,949,000,000	1,929,000,000				7,809,000,000		7,116,000,000
Selling, general, and administrative														636,000,000		513,000,000
Non-service pension and postretirement benefit costs														0		0
Other expense (income), net														14,000,000		83,000,000
Receivables														31,000,000		(215,000,000)
Net cash provided by operating activities														629,000,000		484,000,000
Change in restricted cash														(1,000,000)		(1,000,000)
Proceeds from deferred purchase price of factored receivables														0		0
Net cash used by investing activities														(413,000,000)		(340,000,000)
Increase (decrease) in cash, cash equivalents and restricted cash														(32,000,000)		60,000,000
Cash, cash equivalents and restricted cash, January 1					315,000,000	[1]				347,000,000	[1]	315,000,000	[1]	347,000,000	[1]	287,000,000
Cash, cash equivalents and restricted cash, December 31	[1]						315,000,000							315,000,000		347,000,000
ASU 2016-18 | Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Receivables														0		0
Net cash provided by operating activities														0		0
Change in restricted cash														1,000,000		1,000,000
Proceeds from deferred purchase price of factored receivables														0		0
Net cash used by investing activities														1,000,000		1,000,000
Increase (decrease) in cash, cash equivalents and restricted cash														1,000,000		1,000,000
Cash, cash equivalents and restricted cash, January 1					3,000,000	[1]				2,000,000	[1]	3,000,000	[1]	2,000,000	[1]	1,000,000
Cash, cash equivalents and restricted cash, December 31	[1]						3,000,000							3,000,000		2,000,000
ASU 2016-15 | Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Receivables														(112,000,000)		(110,000,000)
Net cash provided by operating activities														(112,000,000)		(110,000,000)
Change in restricted cash														0		0
Proceeds from deferred purchase price of factored receivables														112,000,000		110,000,000
Net cash used by investing activities														112,000,000		110,000,000
Increase (decrease) in cash, cash equivalents and restricted cash														0		0
Cash, cash equivalents and restricted cash, January 1					$ 0	[1]				$ 0	[1]	0	[1]	0	[1]	0
Cash, cash equivalents and restricted cash, December 31	[1]						0							0		0
ASU 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Inventories																	$ 815,000,000
Prepayments and other current assets																	294,000,000
Accumulated deficit																	(1,008,000,000)
ASU 2014-09 | Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated deficit																	1,000,000
ASU 2016-16
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect																	$ 1,000,000
ASU 2017-07
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of sales (exclusive of depreciation and amortization)														7,812,000,000		7,126,000,000
Selling, general, and administrative														638,000,000		514,000,000
Non-service pension and postretirement benefit costs														16,000,000		84,000,000
Other expense (income), net														(2,000,000)		(1,000,000)
ASU 2017-07 | As Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of sales (exclusive of depreciation and amortization)														7,815,000,000		7,133,000,000
Selling, general, and administrative														650,000,000		590,000,000
Non-service pension and postretirement benefit costs														0		0
Other expense (income), net														(1,000,000)		0
ASU 2017-07 | Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of sales (exclusive of depreciation and amortization)														(3,000,000)		(7,000,000)
Selling, general, and administrative														(12,000,000)		(76,000,000)
Non-service pension and postretirement benefit costs														16,000,000		84,000,000
Other expense (income), net														(1,000,000)		$ (1,000,000)
Product returns | ASU 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Inventories		0										0
Prepayments and other current assets		(44,000,000)										(44,000,000)
Accrued expenses and other current liabilities		(44,000,000)										(44,000,000)
Accumulated deficit		0										0
Net sales and operating revenues												2,000,000
Cost of sales (exclusive of depreciation and amortization)												(2,000,000)
Overtime recognition | ASU 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Inventories		8,000,000					(5,000,000)					8,000,000		(5,000,000)
Prepayments and other current assets		(9,000,000)					6,000,000					(9,000,000)		6,000,000
Accrued expenses and other current liabilities		0										0
Accumulated deficit		(1,000,000)					$ 1,000,000					(1,000,000)		$ 1,000,000
Net sales and operating revenues												3,000,000
Cost of sales (exclusive of depreciation and amortization)												(3,000,000)
Balances Without Adoption of ASC Topic 606 | ASU 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Inventories		2,253,000,000										2,253,000,000
Prepayments and other current assets		537,000,000										537,000,000
Accrued expenses and other current liabilities		957,000,000										957,000,000
Accumulated deficit		$ (1,014,000,000)										(1,014,000,000)
Net sales and operating revenues												11,768,000,000
Cost of sales (exclusive of depreciation and amortization)												$ 10,066,000,000

[1] Cash and cash equivalents include highly liquid investments with a maturity of three months or less at the date of purchase.