DERIVATIVE COMMODITY INSTRUMENTS (Tables)

12 Months Ended

Dec. 31, 2017

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Gain (Loss) on Derivative Instruments

The following table details gain (loss) on derivative instruments, net, as follows:

Years ended December 31, (in thousands)	2017			2016			2015
Open non-cash mark-to-market losses on derivative instruments	$	(10,759	)	$	(71,190	)	$	(281,752	)
Closed gains (losses) on derivative instruments	(15,634		)	(17,287		)	397,045
Gain (loss) on derivative instruments, net	$	(26,393	)	$	(88,477	)	$	115,293

Schedule of Offsetting Liabilities

The following tables detail the offsetting of derivative assets and liabilities as well as the fair values of derivatives on the balance sheets:

(in thousands)	December 31, 2017
										Gross Amounts Not Offset in the Balance Sheets
	Gross Amounts Recognized at Fair Value			Gross Amounts Offset in the Balance Sheets			Net Amounts Presented in the Balance Sheets			Financial Instruments		Cash Collateral Received		Net Fair Value Presented in the Balance Sheets
Derivatives not designated as hedging instruments
Assets
Derivative instruments	$	1,758		$	(1,758	)	$	—		$	—	$	—	$	—
Noncurrent derivative instruments	42			(42		)	—			—		—		—
Total derivative assets	$	1,800		$	(1,800	)	$	—		$	—	$	—	$	—
Liabilities
Derivative instruments	73,137			(1,758		)	71,379			—		—		71,379
Noncurrent derivative instruments	8,928			(42		)	8,886			—		—		8,886
Total derivative liabilities	82,065			(1,800		)	80,265			—		—		80,265
Total derivatives	$	(80,265	)	$	—		$	(80,265	)	$	—	$	—	$	(80,265	)

(in thousands)	December 31, 2016
										Gross Amounts Not Offset in the Balance Sheets
	Gross Amounts Recognized at Fair Value			Gross Amounts Offset in the Balance Sheets			Net Amounts Presented in the Balance Sheets			Financial Instruments		Cash Collateral Received		Net Fair Value Presented in the Balance Sheets
Derivatives not designated as hedging instruments
Assets
Derivative instruments	$	1,756		$	(1,706	)	$	50		$	—	$	—	$	50
Liabilities
Derivative instruments	67,173			(1,706		)	65,467			—		—		65,467
Noncurrent derivative instruments	3,006			—			3,006			—		—		3,006
Total derivative liabilities	70,179			(1,706		)	68,473			—		—		68,473
Total derivatives	$	(68,423	)	$	—		$	(68,423	)	$	—	$	—	$	(68,423	)

Schedule of Offsetting Assets

The following tables detail the offsetting of derivative assets and liabilities as well as the fair values of derivatives on the balance sheets:

(in thousands)	December 31, 2017
										Gross Amounts Not Offset in the Balance Sheets
	Gross Amounts Recognized at Fair Value			Gross Amounts Offset in the Balance Sheets			Net Amounts Presented in the Balance Sheets			Financial Instruments		Cash Collateral Received		Net Fair Value Presented in the Balance Sheets
Derivatives not designated as hedging instruments
Assets
Derivative instruments	$	1,758		$	(1,758	)	$	—		$	—	$	—	$	—
Noncurrent derivative instruments	42			(42		)	—			—		—		—
Total derivative assets	$	1,800		$	(1,800	)	$	—		$	—	$	—	$	—
Liabilities
Derivative instruments	73,137			(1,758		)	71,379			—		—		71,379
Noncurrent derivative instruments	8,928			(42		)	8,886			—		—		8,886
Total derivative liabilities	82,065			(1,800		)	80,265			—		—		80,265
Total derivatives	$	(80,265	)	$	—		$	(80,265	)	$	—	$	—	$	(80,265	)

(in thousands)	December 31, 2016
										Gross Amounts Not Offset in the Balance Sheets
	Gross Amounts Recognized at Fair Value			Gross Amounts Offset in the Balance Sheets			Net Amounts Presented in the Balance Sheets			Financial Instruments		Cash Collateral Received		Net Fair Value Presented in the Balance Sheets
Derivatives not designated as hedging instruments
Assets
Derivative instruments	$	1,756		$	(1,706	)	$	50		$	—	$	—	$	50
Liabilities
Derivative instruments	67,173			(1,706		)	65,467			—		—		65,467
Noncurrent derivative instruments	3,006			—			3,006			—		—		3,006
Total derivative liabilities	70,179			(1,706		)	68,473			—		—		68,473
Total derivatives	$	(68,423	)	$	—		$	(68,423	)	$	—	$	—	$	(68,423	)

Schedule of Hedging Transactions

As of December 31, 2017, Energen entered into the following transactions for 2018 and subsequent years:

Production Period	Description	Total Hedged Volumes		Average Contract Price
Oil
2018	NYMEX Three-Way Collars	13,500	MBbl
	Ceiling sold price (call)			$60.04 Bbl
	Floor purchased price (put)			$45.47 Bbl
	Floor sold price (put)			$35.47 Bbl
2019	NYMEX Three-Way Collars	4,680	MBbl
	Ceiling sold price (call)			$60.84 Bbl
	Floor purchased price (put)			$45.00 Bbl
	Floor sold price (put)			$35.00 Bbl
Oil Basis Differential
2018	WTI/WTI Basis Swaps	10,800	MBbl	$(1.01) Bbl
2019	WTI/WTI Basis Swaps	4,680	MBbl	$(0.44) Bbl
Natural Gas Liquids
2018	Liquids Swaps	105.8	MMGal	$0.59 Gal
2019	Liquids Swaps	25.2	MMGal	$0.66 Gal
Natural Gas
2018	Basin Specific Swaps - Permian	3.6	Bcf	$2.56 Mcf
WTI - West Texas Intermediate/Midland, WTI - West Texas Intermediate/Cushing