Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2018

Schedule of Major Customers [Table Text Block]

The Company had the following major customers and sales to entities under common ownership, which accounted for 10 percent or more of its total oil, gas, and NGL production revenue for at least one of the periods presented:



	For the Years Ended December 31,
	2018		2017		2016
Major customer #1⁽¹⁾	18	%	6	%	—	%
Major customer #2⁽¹⁾	10	%	10	%	5	%
Group #1 of entities under common ownership⁽²⁾	18	%	17	%	15	%
Group #2 of entities under common ownership ⁽²⁾	12	%	8	%	8	%

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⁽¹⁾	These major customers are purchasers of a portion of the Company’s production from its Permian region.


⁽²⁾	In the aggregate, these groups of entities under common ownership represented more than 10 percent of total oil, gas, and NGL production revenue for at least one of the periods presented; however, no individual entity comprising either group represented more than 10 percent of the Company’s total oil, gas, and NGL production revenue.

Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block]

The accompanying statements of operations line items that were adjusted as a result of the adoption of ASU 2017-07 for the years ended December 31, 2017, and 2016 are summarized as follows:



	For the Year Ended December 31, 2017						For the Year Ended December 31, 2016
	As Reported			As Adjusted			As Reported			As Adjusted
	(in thousands)
Operating expenses:
Exploration	$	56,179		$	54,713		$	65,641		$	64,970
General and administrative	$	120,585		$	117,283		$	126,428		$	124,828
Total operating expenses	$	1,297,865		$	1,293,097		$	2,276,765		$	2,274,494

Income (loss) from operations	$	(168,489	)	$	(163,721	)	$	(1,059,315	)	$	(1,057,044	)

Other non-operating income (expense), net	$	3,968		$	(800	)	$	362		$	(1,909	)