Significant Commitments by Category (Detail) $ in Thousands	Dec. 31, 2017 USD ($)
Minimum Rental Commitments
2017	$ 241
2018	78
2019	47
2020	0
2021	0
Thereafter	0
Total	366
Gathering and Intermediate Transportation [Member]
Commitments
Contractual Commitments Future Minimum Payments Due Current	10,376
2018	11,702
2019	12,962
2020	12,962
2021	12,962
Thereafter	63,712
Total	124,676
Drilling carry [Member]
Commitments
Contractual Commitments Future Minimum Payments Due Current	27,777
2018	12,595
2019	1,305
2020	0
2021	0
Thereafter	0
Total	41,677
Other Commitments
Commitments
Contractual Commitments Future Minimum Payments Due Current	157
2018	50
2019	50
2020	5
2021	0
Thereafter	0
Total	262
Contract Drilling [Member]
Commitments
Contractual Commitments Future Minimum Payments Due Current	37,907
2018	0
2019	0
2020	0
2021	0
Thereafter	0
Total	$ 37,907