Significant Commitments by Category (Detail) $ in Thousands	Dec. 31, 2015 USD ($)
Minimum Rental Commitments
2015	$ 2,606
2016	2,542
2017	2,329
2018	1,341
2019	0
Thereafter	0
Total	8,818
Contract Drilling
Commitments
Contractual Commitments Future Minimum Payments Due Current	3,984
2016	0
2017	0
2018	0
2019	0
Thereafter	0
Total	3,984
Gathering and Intermediate Transportation [Member]
Commitments
Contractual Commitments Future Minimum Payments Due Current	15,328
2016	12,319
2017	12,319
2018	12,319
2019	12,352
Thereafter	63,652
Total	128,289
Firm Transportation Commitments
Commitments
Contractual Commitments Future Minimum Payments Due Current	1,098
2016	1,095
2017	1,095
2018	1,095
2019	1,098
Thereafter	8,580
Total	14,061
Drilling carry [Member]
Commitments
Contractual Commitments Future Minimum Payments Due Current	1,900
2016	8,764
2017	0
2018	0
2019	0
Thereafter	0
Total	10,664
Other Commitments
Commitments
Contractual Commitments Future Minimum Payments Due Current	459
2016	274
2017	71
2018	0
2019	0
Thereafter	0
Total	$ 804