Energen Employee Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2018

Defined Benefit Plan Disclosure [Line Items]

Changes in Projected Benefit Obligations, Fair Value of Plan Assets, and Funded Status of Plan [Table Text Block]

Benefit Obligations: The following tables set forth the funded status of Energen’s postretirement health care and life insurance benefit plans and their reconciliation with the related amounts in the Company’s consolidated financial statements:

	One Month Ended December 31, 2018
	(in thousands)
Change in Benefit Obligation
Balance as of November 29, 2018	$	5,373
Service cost	1
Interest cost	19
Actuarial gain	(35		)
Plan amendments	—
Curtailment gain	—
Benefits paid	(7		)
Balance at December 31, 2018	$	5,351
Change in Plans' Assets
Fair value of plan assets at November 29, 2018	$	8,317
Actual return (loss) on plan assets	(90		)
Benefits paid	(7		)
Fair value of plan assets at December 31, 2018	$	8,220
Funded status of plans	$	2,869

	One Month Ended December 31, 2018
	(in thousands)
Amounts recognized on consolidated balance sheets:
Noncurrent assets recognized	$	2,869
Amounts recognized to accumulated other comprehensive income:
Prior service credit, net of taxes	$	—
Net actuarial loss, net of taxes	74
Total accumulated other comprehensive income	$	74

Other changes in plan assets and projected benefit obligations recognized in other comprehensive income were as follows:

	One Month Ended December 31, 2018
	(in thousands)
Postretirement Benefit Plans
Net actuarial (gain) loss experienced during the year	$	74
Net actuarial loss recognized as expense	—
Prior service cost recognized as income	—
Prior service credit during the year	—
Prior service cost amortization	—
Total recognized in other comprehensive income	$	74

Schedule of Net Benefit Costs [Table Text Block]

The components of net periodic benefit cost were as follows:

	One Month Ended December 31, 2018
	(in thousands)
Postretirement Benefit Plans
Components of net periodic benefit cost:
Service cost	$	1
Interest cost	19
Expected long-term return on assets	(19		)
Prior service cost amortization	—
Actuarial gain amortization	—
Settlement charge	—
Curtailment gain	—
Net periodic (income) expense	$	1

weighted average assumptions defined benefti [Table Text Block]

The weighted average rate assumptions to determine net periodic benefit costs were as follows:

	One Month Ended December 31, 2018
Postretirement Benefit Plans
Discount rate	4.55	%
Expected long-term return on plan assets	4.55	%

The weighted average assumptions used to determine the postretirement benefit obligations at the measurement date were as follows:

	One Month Ended December 31, 2018
Discount rate	4.55	%

Schedule of Allocation of Plan Assets [Table Text Block]

Energen sought to maintain an appropriate level of diversification to minimize the risk of large losses in a single asset class. Accordingly, plan assets for the postretirement health care and life insurance benefit plan do not have a concentration of assets in a single entity, industry, commodity or class of investment find.

	Target		As of December 31, 2018
Asset category:
Equity securities	21	%	20	%
Debt securities	74	%	76	%
Other	5	%	4	%
Total	100	%	100	%

plan assets included in funded status [Table Text Block]

Plan assets included in the funded status postretirement benefit plans were as follows:

	December 31, 2018
(in thousands)	Level 1		Level 2		Total
United States equities	$	146	$	—	$	146
Global equities	1,461		—		1,461
Fixed income	6,256		—		6,256
Other	357		—		357
Total	$	8,220	$	—	$	8,220