Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

The following table is a listing of the Company’s assets and liabilities that are measured at fair value in the accompanying balance sheets and where they are classified within the fair value hierarchy as of December 31, 2017:

	Level 1		Level 2		Level 3
	(in thousands)
Assets:
Derivatives (1)	$	—	$	104,628	$	—
Liabilities:
Derivatives (1)	$	—	$	243,984	$	—

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⁽¹⁾  This represents a financial asset or liability that is measured at fair value on a recurring basis.

The following table is a listing of the Company’s assets and liabilities that are measured at fair value in the accompanying balance sheets and where they are classified within the fair value hierarchy as of December 31, 2016:

	Level 1		Level 2		Level 3
	(in thousands)
Assets:
Derivatives (1)	$	—	$	122,096	$	—
Total property and equipment, net (2)	$	—	$	—	$	88,205
Liabilities:
Derivatives (1)	$	—	$	213,804	$	—

____________________________________________

⁽¹⁾  This represents a financial asset or liability that is measured at fair value on a recurring basis.

⁽²⁾  This represents a non-financial asset that is measured at fair value on a nonrecurring basis.

^[1],[2],[3]

Abandonment And Impairment Of Unproved Properties [Table Text Block]

The following table presents abandonment and impairment of unproved properties expense recorded for the periods presented:

	For the Years Ended December 31,
	2017		2016		2015
	(in millions)
Abandonment and impairment of unproved properties	$	12.3	$	80.4	$	78.6

Long Term Debt Fair Value [Table Text Block]

The following table reflects the fair value of the Senior Notes and Senior Convertible Notes measured using Level 1 inputs based on quoted secondary market trading prices. These notes were not presented at fair value on the accompanying balance sheets as of December 31, 2017, or 2016, as they are recorded at carrying value, net of any unamortized discounts and deferred financing costs. Please refer to Note 5 – Long-Term Debt for additional discussion.

	As of December 31,
	2017				2016
	Principal Amount		Fair Value		Principal Amount		Fair Value
	(in thousands)
6.50% Senior Notes due 2021	$	344,611	$	351,682	$	346,955	$	354,546
6.125% Senior Notes due 2022	$	561,796	$	571,627	$	561,796	$	570,925
6.50% Senior Notes due 2023	$	394,985	$	403,434	$	394,985	$	403,134
5.0% Senior Notes due 2024	$	500,000	$	483,440	$	500,000	$	475,975
5.625% Senior Notes due 2025	$	500,000	$	494,355	$	500,000	$	485,000
6.75% Senior Notes due 2026	$	500,000	$	516,350	$	500,000	$	516,565
1.50% Senior Convertible Notes due 2021	$	172,500	$	168,291	$	172,500	$	202,189

[1] This represents a financial asset or liability that is measured at fair value on a recurring basis.

[2] This represents a financial asset or liability that is measured at fair value on a recurring basis.

[3] This represents a non-financial asset that is measured at fair value on a nonrecurring basis.