CONCENTRATION OF RISK Accounts Receivable, net of Allowance for Doubtful Accounts (Tables)

12 Months Ended

Dec. 31, 2016

Concentration Risks, Types, No Concentration Percentage [Abstract]

Accounts Payable, Accrued Liabilities, and Other Liabilities Disclosure, Current [Text Block]

Other Accrued Expenses. The following table presents the components of other accrued expenses:

	As of December 31,
	2016		2015
	(in thousands)
Employee benefits	$	22,282	$	17,774
Asset retirement obligations	9,775		5,460
Environmental expenses	3,238		4,143
Other	3,330		1,332
Other accrued expenses	$	38,625	$	28,709

Accounts Receivable [Table Text Block]

Accounts Receivable. The following table presents the components of accounts receivable, net of allowance for doubtful accounts:

	As of December 31,
	2016			2015
	(in thousands)
Crude oil, natural gas and NGLs sales	$	97,520		$	41,873
Joint interest billings	20,118			35,017
Derivative counterparties	10,266			24,437
Income tax receivable	11,505			—
Insurance reimbursement	—			879
Other	6,173			4,077
Allowance for doubtful accounts	(2,190		)	(2,009		)
Accounts receivable, net	$	143,392		$	104,274

Individual Customers Constituting 10% or more of Total Revenue [Table Text Block]

Major Customers. The following table presents the individual customers constituting 10 percent or more of total revenues:

	Year Ended December 31,
Customer	2016		2015		2014
Suncor Energy Marketing, Inc.	22.3	%	14.3	%	19.7	%
DCP Midstream, LP	20.2	%	13.2	%	15.1	%
Aka Energy Group, LLC	13.4	%	—	%	—	%
Concord Energy, LLC	13.4	%	23.2	%	18.3	%
Bridger Energy, LLC	11.5	%	—	%	—	%
Shell Trading Company	—	%	13.8	%	—	%
Teppco Crude Oil, LLC	—	%	—	%	12.9	%

Notes Receivable [Table Text Block]

The following table presents information regarding our note receivable outstanding:

	As of December 31,
	2016			2015
	(in thousands)
Principal and PIK Interest outstanding at beginning of period	$	43,069		$	39,707
PIK Interest	969			3,362
Principal and PIK Interest outstanding at end of period	44,038			43,069
Allowance for uncollectible notes receivable	(44,038		)	—
Note receivable, net	$	—		$	43,069