E. COMMODITY DERIVATIVE INSTRUMENTS (Details)	Dec. 31, 2017 USD ($) bbl MMBbls	Dec. 31, 2016 USD ($) bbl MMBbls	Dec. 31, 2015 USD ($) bbl MMBbls
Reverse Swaps
Volume | MMBbls	0	0	50,441
Price(NYMEX)	$ 0	$ 0	$ 4.33
Swaps
Volume | MMBbls	0	298,957	435,207
Price(NYMEX)	$ 0	$ 3.28	$ 3.15	[1]
Volume | bbl	0	138,286	44,966
Price(LLS)	$ 0	$ 62.27	$ 56.9
3-Way Collars
Volume | MMBbls	67,361	0	0
Ceiling sold price (call) (NYMEX)	$ 4.03	$ 0	$ 0
Floor purchased price (put) (NYMEX)	3.5	0	0
Floor sold price (short put) (NYMEX)	$ 3	$ 0	$ 0
Volume | bbl	113,029	0	0
Ceiling sold price (call) (WTI)	$ 77	$ 0	$ 0
Floor purchased price (put) (WTI)	60	0	0
Floor sold price (short put) (WTI)	$ 45	$ 0	$ 0

[1] Price is a weighted average.