Debt (Schedule of long-term debt instruments) (Details) - USD ($)	1 Months Ended		6 Months Ended		12 Months Ended
	Aug. 31, 2016	May 31, 2016	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2024	Dec. 31, 2021	Dec. 31, 2015
Debt Instrument
Total debt			$ 7,841,000,000				$ 8,162,000,000
Less short-term portion			(576,000,000)				(607,000,000)
Total long-term debt			7,265,000,000				7,555,000,000
Loss on repurchase/redemption of debt securities and amendment of ABL facility			$ 26,000,000	$ 123,000,000
Accounts Receivable Securitization Facility
Debt Instrument
Credit facility interest rate at period end			1.10%
$2.5 billion ABL Facility | URNA and subsidiaries
Debt Instrument
Maximum borrowing capacity			$ 2,500,000,000.0				$ 2,500,000,000.0
7 3/8 percent Senior Notes
Debt Instrument
Stated interest rate			7.375%				7.375%
7 3/8 percent Senior Notes | Interest expense | Forecast
Debt Instrument
Loss on repurchase/redemption of debt securities and amendment of ABL facility	$ 10,000,000
8 1/4 percent Senior Notes
Debt Instrument
Stated interest rate			8.25%				8.25%
7 5/8 percent Senior Notes
Debt Instrument
Stated interest rate			7.625%				7.625%
6 1/8 percent Senior Notes
Debt Instrument
Stated interest rate			6.125%				6.125%
4 5/8 percent Senior Secured Notes
Debt Instrument
Stated interest rate			4.625%				4.625%
5 3/4 percent Senior Notes
Debt Instrument
Stated interest rate			5.75%				5.75%
5 1/2 percent Senior Notes
Debt Instrument
Stated interest rate			5.50%				5.50%
5 7/8 percent Senior Notes
Debt Instrument
Stated interest rate			5.875%				5.875%
Capital leases | URNA and subsidiaries
Debt Instrument
Total debt			$ 85,000,000				$ 96,000,000
7 3/8 Senior Notes and 8 1/4 percent Senior Notes | Interest expense
Debt Instrument
Loss on repurchase/redemption of debt securities and amendment of ABL facility		$ 25,000,000
Credit facility | $2.5 billion ABL Facility
Debt Instrument
Current borrowing capacity under credit facility			$ 1,000,000,000
Credit facility interest rate at period end			2.00%
Letters of credit outstanding			$ 37,000,000
Average outstanding amount			$ 1,300,000,000
Weighted average interest rate, long-term			2.20%
ABL Facility maximum month-end outstanding amount			$ 1,600,000,000
Credit facility | $2.5 billion ABL Facility | URNA and subsidiaries
Debt Instrument
Total debt			1,410,000,000				1,579,000,000
Senior notes | 7 3/8 percent Senior Notes
Debt Instrument
Face amount		550,000,000
Senior notes | 7 3/8 percent Senior Notes | URNA and subsidiaries
Debt Instrument
Total debt			198,000,000				740,000,000
Senior notes | 7 3/8 percent Senior Notes | Forecast
Debt Instrument
Face amount	$ 200,000,000
Senior notes | 8 1/4 percent Senior Notes | URNA and subsidiaries
Debt Instrument
Total debt			0				315,000,000
Senior notes | 7 5/8 percent Senior Notes | URNA and subsidiaries
Debt Instrument
Total debt			1,308,000,000				1,306,000,000
Senior notes | 6 1/8 percent Senior Notes | URNA and subsidiaries
Debt Instrument
Total debt			936,000,000				937,000,000
Senior notes | 5 3/4 percent Senior Notes | URNA and subsidiaries
Debt Instrument
Total debt			839,000,000				838,000,000
Senior notes | 5 1/2 percent Senior Notes | URNA and subsidiaries
Debt Instrument
Total debt			792,000,000				791,000,000
Senior secured notes | 4 5/8 percent Senior Secured Notes | URNA and subsidiaries
Debt Instrument
Total debt			990,000,000				989,000,000
Senior subordinated notes | 5 7/8 percent Senior Notes
Debt Instrument
Proceeds from issuance of long-term debt		$ 741,000,000
Debt redemption percentage		101.00%
Senior subordinated notes | 5 7/8 percent Senior Notes | URNA and subsidiaries
Debt Instrument
Total debt			739,000,000				0
Face amount		$ 750,000,000
Senior subordinated notes | 5 7/8 percent Senior Notes | Forecast
Debt Instrument
Debt redemption percentage					100.00%	102.938%
Accounts receivable facility | Accounts Receivable Securitization Facility
Debt Instrument
Current borrowing capacity under credit facility			16,000,000
Average outstanding amount under facility			$ 521,000,000
Weighted average interest rate, short-term			1.10%
A/R Securitization maximum month-end outstanding amount			$ 544,000,000
Collateral amount			560,000,000
Accounts receivable facility | Accounts Receivable Securitization Facility | URNA and subsidiaries
Debt Instrument
Total debt			$ 544,000,000				$ 571,000,000