Commitments and Contingencies (Other Commitments) (Details) $ in Thousands, Mcfe in Millions, MMcfe in Millions, MBbls in Millions	6 Months Ended	12 Months Ended
	Dec. 31, 2015 USD ($) ft²	Dec. 31, 2015 USD ($) ft² MMcfe item	Dec. 31, 2014 USD ($) Mcfe MBbls	Dec. 31, 2013 USD ($)	Sep. 01, 2015 USD ($)	Aug. 10, 2015 USD ($)
Other Commitments
Rent expense		$ 6,300	$ 2,600	$ 1,800
Summary of contractual obligations
2016	$ 2,776,300	2,776,300
2017	14,200	14,200
2018	8,800	8,800
2019	7,200	7,200
2020	6,400	6,400
Thereafter	67,200	67,200
Total future commitments	$ 2,880,100	2,880,100
Interest Expense		$ 180,285	$ 115,559	$ 99,448
Downtown Houston TX
Other Commitments
Office space (in square feet) | ft²	73,000	73,000
Average annual rent over entire lease term		$ 1,600
Summary of contractual obligations
Total future commitments	$ 800	800
Office and Production Equipment
Summary of contractual obligations
Total future commitments	700	700
South Texas Agreements
Other Commitments
Term of agreement			10 years
Minimum volume required (in Bcfe) | Mcfe			88.5
Minimum volume required (in MBbl) | MBbls			5,150
Summary of contractual obligations
Total future commitments	30,200	$ 30,200
Properties in Core Operating Areas
Other Commitments
Minimum volume required (in Bcfe) | MMcfe		6.8
Summary of contractual obligations
Total future commitments	6,300	$ 6,300
Office and Equipment Leases
Summary of contractual obligations
2016	1,400	1,400
2017	100	100
Total future commitments	1,500	1,500
Operating commitments
Summary of contractual obligations
2016	8,800	8,800
2017	9,800	9,800
2018	4,700	4,700
2019	3,200	3,200
2020	2,600	2,600
Thereafter	7,400	7,400
Total future commitments	36,500	36,500
Other
Summary of contractual obligations
2016	14,000	14,000
2017	4,300	4,300
2018	4,100	4,100
2019	4,000	4,000
2020	3,800	3,800
Thereafter	59,800	59,800
Total future commitments	90,000	$ 90,000
HPIP Gonzales Holdings, LLC
Drilling and Completion
Minimum number of wells drilled | item		1
Revolving Credit Facility
Summary of contractual obligations
2016	902,100	$ 902,100
Total future commitments	$ 902,100	$ 902,100
Weighted average interest rate (as a percent)	4.02%	4.02%	2.40%
Term Loan Facility
Summary of contractual obligations
2016	$ 700,000	$ 700,000
Total future commitments	700,000	700,000
2017 Senior Notes
Summary of contractual obligations
2016	350,000	350,000
Total future commitments	350,000	350,000
2019 Senior Notes
Summary of contractual obligations
2016	577,900	577,900
Total future commitments	577,900	577,900
2020 Senior Notes
Summary of contractual obligations
2016	222,100	222,100
Total future commitments	222,100	222,100
Other Operating Income (Expense) | South Texas Agreements
Drilling and Completion
Minimum delivery commitment shortfall penalty		(3,000)
Other Operating Income (Expense) | Properties in Core Operating Areas
Drilling and Completion
Minimum delivery commitment shortfall penalty		$ (1,300)
Liabilities Subject to Compromise
Drilling and Completion
Rejection of secured rig and servicing contracts						$ 29,000
Other Commitments
Office leases					$ 3,600
Summary of contractual obligations
Interest Expense	$ 0