DEBT - 2014 Credit Facilities (Details) $ in Millions	1 Months Ended		3 Months Ended							9 Months Ended		21 Months Ended
	Feb. 28, 2017 USD ($)	Aug. 31, 2016 USD ($)	Sep. 30, 2017 USD ($) item	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Sep. 30, 2017 USD ($) item	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) item	Nov. 01, 2017 USD ($)
Debt
Aggregate payments of term loan										$ 91	$ 329
2014 Credit Facilities (Secured First Lien)
Debt
Maximum borrowing capacity			$ 2,000							2,000		$ 2,000
Borrowing base													$ 2,300
Maximum principal amount of unsecured senior notes that may be repurchased at less than a significant discount to par from the net cash proceeds from asset sales			$ 140							$ 140		$ 140
Minimum percent of asset sale proceeds must be in cash			75.00%							75.00%		75.00%
Percentage of proceeds from non-borrowing base asset sales used to repurchase debt if leverage ratio less than 4:00 to 1:00			40.00%							40.00%		40.00%
Leverage ratio less than of which the percent of net cash proceeds from non-borrowing base asset sales that may be used to repurchase unsecured senior at a discount to par, general corporate purposes or oil and gas expenditures falls to 40%			4.00%							4.00%		4.00%
Approval percentage measured by total exposure of lenders for approval of increases in borrowing base			80.00%							80.00%		80.00%
Approval percentage measured by total exposure of lenders to request a special redetermination			67.00%							67.00%		67.00%
Percent of commitment required to decrease or affirm the borrowing base			67.00%							67.00%		67.00%
Number of consecutive redeterminations between which CRC or lenders can request a special redetermination | item			3							3		3
Financial performance covenants
Minimum monthly liquidity			$ 250							$ 250		$ 250
Percent of net cash proceeds from asset sales which must be used (other than permitted development joint ventures and other transactions) to repay loans outstanding under the 2014 First-Out Credit Facilities			100.00%							100.00%		100.00%
Maximum percent of net cash proceeds from non-borrowing base asset sales that may be used to repurchase unsecured senior notes at a discount to par, general corporate purposes or oil and gas expenditures			50.00%							50.00%		50.00%
Maximum additional non-Credit Facility indebtedness			$ 50							$ 50		$ 50
Amount of cash on hand above which amounts owed under the Revolving Credit Facility must be repaid			$ 150							$ 150		$ 150
2014 Credit Facilities (Secured First Lien) | Federal fund rate
Debt
Interest rate added to variable rate basis (as a percent)										0.50%
2014 Credit Facilities (Secured First Lien) | One-Month LIBOR
Debt
Interest rate added to variable rate basis (as a percent)										1.00%
2014 Credit Facilities (Secured First Lien) | Quarter ending through September 30, 2017
Financial performance covenants
Maximum leverage ratio			3.25							3.25		3.25
Minimum interest coverage ratio			1.20							1.20		1.20
2014 Credit Facilities (Secured First Lien) | Quarter ending through December 31, 2017
Financial performance covenants
Maximum leverage ratio			3.25							3.25		3.25
Minimum interest coverage ratio			1.20							1.20		1.20
Minimum asset coverage ratio			1.20							1.20		1.20
2014 Credit Facilities (Secured First Lien) | Quarter ending through March 31, 2018
Financial performance covenants
Maximum leverage ratio			2.25							2.25		2.25
Minimum interest coverage ratio			2.00							2.00		2.00
2014 Credit Facilities (Secured First Lien) | Quarter ending through June 30, 2018
Financial performance covenants
Maximum leverage ratio			2.25							2.25		2.25
Minimum interest coverage ratio			2.00							2.00		2.00
Minimum asset coverage ratio			1.20							1.20		1.20
2014 Credit Facilities (Secured First Lien) | Quarter ending through September 30, 2018
Financial performance covenants
Maximum leverage ratio			2.25							2.25		2.25
Minimum interest coverage ratio			2.00							2.00		2.00
2014 Credit Facilities (Secured First Lien) | Quarter ending through December 31, 2018
Financial performance covenants
Maximum leverage ratio			2.25							2.25		2.25
Minimum interest coverage ratio			2.00							2.00		2.00
Minimum asset coverage ratio			1.20							1.20		1.20
2014 Credit Facilities (Secured First Lien) | 5% Notes Due 2020 and 5.50% Notes Due 2021
Debt
Outstanding amount that triggers accelerated payment			$ 100							$ 100		$ 100
Financial performance covenants
Period before maturity of the specified notes										182 days
Minimum | 2014 Credit Facilities (Secured First Lien)
Financial performance covenants
Total leverage ratio when applicable margins on LIBOR and ABR loans apply			3.00							3.00		3.00
Minimum | 2014 Credit Facilities (Secured First Lien) | Applicable margin on Alternate Base Rate loans
Debt
Interest rate added to variable rate basis (as a percent)										2.50%
Minimum | 2014 Credit Facilities (Secured First Lien) | Applicable margin on LIBOR loans
Debt
Interest rate added to variable rate basis (as a percent)										1.50%
Maximum | 2014 Credit Facilities (Secured First Lien) | Applicable margin on Alternate Base Rate loans
Debt
Interest rate added to variable rate basis (as a percent)										3.50%
Maximum | 2014 Credit Facilities (Secured First Lien) | Applicable margin on LIBOR loans
Debt
Interest rate added to variable rate basis (as a percent)										2.50%
Term Loan Facility | 2014 Credit Facilities (Secured First Lien)
Debt
Maximum borrowing capacity			$ 559							$ 559		$ 559
Quarterly installment payment of Term Loan			25	$ 25	$ 25	$ 25	$ 25	$ 25	$ 25
Aggregate payments of term loan												175
Prepayment of term loan from proceeds of non-core asset sale	$ 16
Prepayment of term loan from proceeds of 2016 Credit Agreement		$ 250
Revolving Credit Facility | 2014 Credit Facilities (Secured First Lien)
Debt
Maximum borrowing capacity			1,400							1,400		1,400
Maximum sub-limit on borrowing capacity for issuance of letters of credit			400							400		400
Increase to maximum borrowing capacity with lender approval			245							$ 245		245
Commitment fees on unused portion of the Revolving Credit Facility										0.50%
Available borrowing capacity, subject to minimum liquidity requirement			$ 431							$ 431		$ 431