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LONG-TERM DEBT (Details) - USD ($)	1 Months Ended			12 Months Ended
LONG-TERM DEBT (Details) - USD ($)	Feb. 29, 2016	Jun. 30, 2015	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Litigation and debt
Long-term debt, gross				$ 8,357,000,000	$ 6,857,000,000
Unamortized discount, net				(24,000,000)	(19,000,000)
Current maturities				(1,450,000,000)
Total long-term debt				6,883,000,000	6,838,000,000
Long term debt matured					107,000,000	$ 690,000,000
Debt instrument issued		$ 1,500,000,000
Net proceeds from issuance of long-term debt		$ 1,480,000,000		1,478,000,000
Dolphin Energy
Litigation and debt
Notional amount of limited recourse guarantees with respect to Dolphin Energy's debt				318,000,000	336,000,000
2.50% senior notes due 2016
Litigation and debt
Long-term debt, gross				700,000,000	700,000,000
4.125% senior notes due 2016
Litigation and debt
Long-term debt, gross				750,000,000	750,000,000
1.75% senior notes due 2017
Litigation and debt
Long-term debt, gross				$ 1,250,000,000	1,250,000,000
Debt instrument interest rate stated percentage				1.75%
1.50% senior notes due 2018
Litigation and debt
Long-term debt, gross				$ 500,000,000	500,000,000
9.25% senior debentures due 2019
Litigation and debt
Long-term debt, gross				116,000,000	116,000,000
4.10% senior notes due 2021
Litigation and debt
Long-term debt, gross				1,249,000,000	1,249,000,000
3.125% senior notes due 2022
Litigation and debt
Long-term debt, gross				813,000,000	813,000,000
2.70% senior notes due 2023
Litigation and debt
Long-term debt, gross				1,191,000,000	1,191,000,000
8.75% medium-term notes due 2023
Litigation and debt
Long-term debt, gross				22,000,000	22,000,000
3.50% senior unsecured notes due 2025
Litigation and debt
Long-term debt, gross				750,000,000
Debt instrument interest rate stated percentage		3.50%
Debt instrument issued		$ 750,000,000
7.2% senior debentures due 2028
Litigation and debt
Long-term debt, gross				82,000,000	82,000,000
8.45% senior notes due 2029
Litigation and debt
Long-term debt, gross				116,000,000	$ 116,000,000
4.625% senior unsecured notes due 2045
Litigation and debt
Long-term debt, gross				$ 750,000,000
Debt instrument interest rate stated percentage		4.625%		4.625%
Debt instrument issued		$ 750,000,000
Variable rate bonds due 2030 (0.02% and 0.04% as of December 31, 2015 and 2014, respectively)
Litigation and debt
Variable interest rate (as a percent)					0.04%
Long-term debt, gross				$ 68,000,000	$ 68,000,000
1.45% senior notes due 2013
Litigation and debt
Debt instrument interest rate stated percentage					1.45%
Long term debt matured			$ 600,000,000
Senior notes due in 2021 and later
Litigation and debt
Notes repurchased			$ 90,000,000			$ 90,000,000
Senior Notes Due 2022 And Later Member
Litigation and debt
Notes repurchased					$ 107,000,000
4.125% and 2.5% Senior Notes due in 2016
Litigation and debt
Retirement of current maturities of long term debt	$ 700,000,000