Components of Selected Balance Sheet Accounts (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010
Other current assets:
Tubular inventory and well materials	$ 14,251		$ 3,600
Prepaid expenses	699		633
Prepaid Expense and Other Assets, Current, Total	14,950		4,233
Other assets:
Debt issuance costs	16,993		14,300
Long-term investments - Rabbi Trust	3,088	[1]	6,440	[1]
Other	51		47
Other assets	20,132		20,787
Accounts payable and accrued liabilities:
Trade accounts payable	30,186		33,831
Drilling costs	30,948		31,770
Royalties	15,235		9,308
Production and franchise taxes	3,495		6,012
Compensation	5,186	[2],[3]	9,631	[2],[3]
Interest	5,964		2,977
Other	3,490		6,132
Accounts payable and accrued liabilities	94,504		99,661
Other liabilities:
Asset retirement obligations	6,283		7,364
Defined benefit pension obligations	1,763	[2]	1,766	[2]
Postretirement health care benefit obligations	3,022	[2]	2,976	[2]
Deferred compensation	3,172	[1]	6,952	[1]
Other	1,647		900
Other liabilities	$ 15,887		$ 19,958

[1] Represents the assets and liabilities of the Company's nonqualified supplemental employee retirement savings plan. Assets of the plan are held in a Rabbi Trust. Shares of the Company's common stock held by the Rabbi Trust are presented as Treasury stock carried at cost.

[2] Includes the combined unfunded benefit obligations under the Company's defined benefit pension and postretirement health care plans of $5.4 million as of December 31, 2011 and 2010. The expense recognized with respect to these plans was $0.4 million, $0.6 million and $0.6 million, for the years ended December 31, 2011, 2010 and 2009, respectively.

[3] Includes employer matching obligations under the Company's defined contribution retirement plan of $0.3 million as of December 31, 2011 and 2010. The expense recognized with respect to this plan was $1.2 million, $1.7 million and $2.3 million for the years ended December 31, 2011, 2010 and 2009, respectively.