Long-Term Debt (Credit Facility as Amended, Amendments and Modifications Narrative) (Details) - USD ($)										1 Months Ended	12 Months Ended
	Nov. 03, 2017	Sep. 29, 2017	Jul. 07, 2017	Jun. 30, 2017	May 12, 2017	May 04, 2017	Mar. 16, 2017	Dec. 30, 2016	Apr. 29, 2016	Aug. 17, 2012	Dec. 31, 2017	Dec. 31, 2016	May 30, 2017	May 18, 2015	Mar. 09, 2015	Jan. 27, 2014	Jan. 26, 2014
Debt Instrument [Line Items]
Issuance of long-term debt											$ 3,100,000,000
Proceeds from QHC spinoff												$ 1,219,000,000
Balance of Remaining Non-extended Term Loans											$ 14,082,000,000
Credit Facility, Revolving Credit Loans [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity													$ 929,000,000
Credit Facility, Term Loan A [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Extinguishment of Debt, Amount					$ 713,000,000	$ 39,000,000		$ 26,000,000
Credit Facility, Term Loan B, Initial Funding [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Balance of Remaining Non-extended Term Loans																	$ 60,000,000
Extinguishment of Debt, Amount										$ 1,600,000,000
Credit Facility, Term Loan F [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount															$ 1,700,000,000
Extinguishment of Debt, Amount							$ 1,445,000,000	48,000,000	$ 190,000,000
Credit Facility, Term Loan G [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount														$ 1,600,000,000
Extinguishment of Debt, Amount	$ 21,000,000	$ 151,000,000	$ 121,000,000	$ 122,000,000		75,000,000		52,000,000
Credit Facility, Term Loan H [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount														$ 2,900,000,000
Extinguishment of Debt, Amount	$ 39,000,000	$ 277,000,000	$ 222,000,000	$ 225,000,000		$ 147,000,000		$ 96,000,000
Credit Facility, Term Loan A, March 6, 2012 Amendment [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Balance of Remaining Non-extended Term Loans																	$ 637,000,000
Credit Facility, Revolving Credit Loans, Third Amendment and Restatement [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity																$ 1,000,000,000
Credit Facility, Revolving Credit Loans, January 27, 2021 [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity													$ 739,000,000
Credit Facility, Term Loan A, Third Amendment and Restatement [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount																1,000,000,000
Credit Facility, Term Loan D, Third Amendment and Restatement [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount																4,600,000,000
Credit Facility, Term Loan E, Third Amendment and Restatement [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount																$ 1,700,000,000
Senior Secured Notes at 6.25, Due 2023 [Member] | Senior Secured Notes [Member]
Debt Instrument [Line Items]
Issuance of long-term debt					900,000,000
Debt Instrument, Face Amount					$ 3,100,000,000		$ 2,200,000,000
Debt Instrument, Interest Rate, Stated Percentage							6.25%