Debt (Schedule of long-term debt instruments) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Debt Instrument
Total debt	$ 7,753,000,000	$ 8,162,000,000
Less short-term portion	(550,000,000)	(607,000,000)
Total long-term debt	$ 7,203,000,000	$ 7,555,000,000
Accounts Receivable Securitization Facility
Debt Instrument
Credit facility interest rate at period end	1.10%
7 3/8 percent Senior Notes
Debt Instrument
Stated interest rate	7.375%	7.375%
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 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%
Credit facility | $2.5 billion ABL Facility
Debt Instrument
Current borrowing capacity under credit facility	$ 1,200,000,000
Credit facility interest rate at period end	2.30%
Letters of credit outstanding	$ 38,000,000
Average outstanding amount	$ 1,400,000,000
Weighted average interest rate, long-term	2.30%
ABL Facility maximum month-end outstanding amount	$ 1,600,000,000
Accounts receivable facility | Accounts Receivable Securitization Facility
Debt Instrument
Current borrowing capacity under credit facility	14,000,000
Average outstanding amount under facility	$ 502,000,000
Weighted average interest rate, short-term	1.10%
A/R Securitization maximum month-end outstanding amount	$ 516,000,000
Collateral amount	530,000,000
URNA and subsidiaries | $2.5 billion ABL Facility
Debt Instrument
Maximum borrowing capacity	2,500,000,000.0	$ 2,500,000,000.0
URNA and subsidiaries | Capital leases
Debt Instrument
Total debt	91,000,000	96,000,000
URNA and subsidiaries | Credit facility | $2.5 billion ABL Facility
Debt Instrument
Total debt	1,228,000,000	1,579,000,000
URNA and subsidiaries | Senior notes | 7 3/8 percent Senior Notes
Debt Instrument
Total debt	741,000,000	740,000,000
URNA and subsidiaries | Senior notes | 8 1/4 percent Senior Notes
Debt Instrument
Total debt	314,000,000	315,000,000
URNA and subsidiaries | Senior notes | 7 5/8 percent Senior Notes
Debt Instrument
Total debt	1,307,000,000	1,306,000,000
URNA and subsidiaries | Senior notes | 6 1/8 percent Senior Notes
Debt Instrument
Total debt	937,000,000	937,000,000
URNA and subsidiaries | Senior notes | 5 3/4 percent Senior Notes
Debt Instrument
Total debt	838,000,000	838,000,000
URNA and subsidiaries | Senior notes | 5 1/2 percent Senior Notes
Debt Instrument
Total debt	791,000,000	791,000,000
URNA and subsidiaries | Senior secured notes | 4 5/8 percent Senior Notes
Debt Instrument
Total debt	990,000,000	989,000,000
URNA and subsidiaries | Accounts receivable facility | Accounts Receivable Securitization Facility
Debt Instrument
Total debt	$ 516,000,000	$ 571,000,000