Long-Term Debt (Schedule of Debt) (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Debt	$ 16,867	$ 16,916
Current maturities of long-term debt	(246)	(235)
Long-term debt	16,621	16,681
Secured Debt [Member] | Credit Facility, Term Loan A [Member]
Debt Instrument [Line Items]
Debt	900	950
Secured Debt [Member] | Credit Facility, Term Loan D [Member]
Debt Instrument [Line Items]
Debt		4,555
Secured Debt [Member] | Credit Facility, Term Loan E [Member]
Debt Instrument [Line Items]
Debt		1,660
Secured Debt [Member] | Credit Facility, Term Loan F [Member]
Debt Instrument [Line Items]
Debt	1,696
Secured Debt [Member] | Credit Facility, Term Loan G [Member]
Debt Instrument [Line Items]
Debt	1,600
Secured Debt [Member] | Credit Facility, Term Loan H [Member]
Debt Instrument [Line Items]
Debt	2,944
Senior Notes [Member] | Senior Notes at 8.0, Due 2019 [Member]
Debt Instrument [Line Items]
Debt	2,016	2,018
Senior Notes [Member] | Senior Notes at 7.125, Due 2020 [Member]
Debt Instrument [Line Items]
Debt	1,200	1,200
Senior Notes [Member] | Senior Notes at 6.875, Due 2022 [Member]
Debt Instrument [Line Items]
Debt	3,000	3,000
Senior Secured Notes [Member] | Senior Secured Notes At 5.125 Due 2018 [Member]
Debt Instrument [Line Items]
Debt	1,600	1,600
Senior Secured Notes [Member] | Senior Secured Notes at 5.125, Due 2021 [Member]
Debt Instrument [Line Items]
Debt	1,000	1,000
Receivables Facility [Member] | Receivables Facility, Name [Member]
Debt Instrument [Line Items]
Debt	606	614
Capital Lease Obligations [Member]
Debt Instrument [Line Items]
Debt	202	228
Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt	$ 103	$ 91