Long-Term Debt (Schedule of Debt) (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Debt	$ 15,363	$ 16,785
Current maturities of long-term debt	(253)	(229)
Long-term debt	15,110	16,556
Secured Debt [Member] | Credit Facility, Term Loan A [Member]
Debt Instrument [Line Items]
Debt	796	844
Secured Debt [Member] | Credit Facility, Term Loan F [Member]
Debt Instrument [Line Items]
Debt	1,481	1,671
Secured Debt [Member] | Credit Facility, Term Loan G [Member]
Debt Instrument [Line Items]
Debt	1,563	1,568
Secured Debt [Member] | Credit Facility, Term Loan H [Member]
Debt Instrument [Line Items]
Debt	2,874	2,884
Line of Credit [Member] | Credit Facility, Revolving Credit Loans [Member]
Debt Instrument [Line Items]
Debt	(10)	147
Senior Notes [Member] | Senior Notes at 8.0, Due 2019 [Member]
Debt Instrument [Line Items]
Debt	1,919	1,992
Senior Notes [Member] | Senior Notes at 7.125, Due 2020 [Member]
Debt Instrument [Line Items]
Debt	1,187	1,186
Senior Notes [Member] | Senior Notes at 6.875, Due 2022 [Member]
Debt Instrument [Line Items]
Debt	2,926	2,921
Senior Secured Notes [Member] | Senior Secured Notes At 5.125 Due 2018 [Member]
Debt Instrument [Line Items]
Debt	697	1,587
Senior Secured Notes [Member] | Senior Secured Notes at 5.125, Due 2021 [Member]
Debt Instrument [Line Items]
Debt	970	967
Receivables Facility [Member] | Receivables Facility, Name [Member]
Debt Instrument [Line Items]
Debt	673	699
Capital Lease Obligations [Member]
Debt Instrument [Line Items]
Debt	191	227
Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt	$ 96	$ 92