Significant Commitments by Category (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011
Minimum Rental Commitments
2012	$ 3,120
2013	2,283
2014	1,737
2015	1,628
2016	1,456
Thereafter	1,963
Total	12,187
Drilling Commitments
Commitments
2012	23,820
2013	59
Total	23,879
Firm Transportation Commitments
Commitments
2012	10,255
2013	8,805
2014	6,137
2015	5,137
2016	4,271
Thereafter	30,957
Total	$ 65,562

Contractual Commitments Future Minimum Payments Due

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Contractual Commitments Future Minimum Payments Due Current

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Contractual Commitments Future Minimum Payments Due In Five Years

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Contractual Commitments Future Minimum Payments Due In Four Years

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Contractual Commitments Future Minimum Payments Due In Three Years

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Contractual Commitments Future Minimum Payments Due In Two Years

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Contractual Commitments Future Minimum Payments Due Thereafter

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The total of future contractually required payments on leases defined as operating.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 13

-Paragraph 122

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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For leases having an initial or remaining non-cancelable letter-terms in excess of one year, required rental payments due within one year of the balance sheet date relating to leases defined as operating.

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For leases having an initial or remaining non-cancelable letter-terms in excess of one year, required rental payments due within the fifth year of the balance sheet date relating to leases defined as operating.

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For leases having an initial or remaining non-cancelable letter-terms in excess of one year, required rental payments due within the fourth year of the balance sheet date relating to leases defined as operating.

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For leases having an initial or remaining non-cancelable letter-terms in excess of one year, required rental payments due within the second year of the balance sheet date relating to leases defined as operating.

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For leases having an initial or remaining non-cancelable letter-terms in excess of one year, required rental payments due after the fifth year from the balance sheet date on leases defined as operating.

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