Components of Selected Balance Sheet Accounts (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Other current assets:
Tubular inventory and well materials	$ 4,033		$ 14,251
Prepaid expenses	562		699
Prepaid Expense and Other Assets, Current, Total	4,595		14,950
Other assets:
Debt issuance costs	13,186		16,993
Assets of supplemental employee retirement plan ("SERP")	3,237	[1]	3,088	[1]
Other	1,511		51
Other assets	17,934		20,132
Accounts payable and accrued liabilities:
Trade accounts payable	37,835		30,186
Drilling costs	37,703		30,948
Royalties	14,390		15,235
Production and franchise taxes	2,874		3,495
Compensation - related	6,853	[2],[3]	5,186	[2],[3]
Interest	5,828		5,964
Preferred stock dividends	1,687		0
Other	4,485		3,490
Accounts payable and accrued liabilities	111,655		94,504
Other liabilities:
Firm transportation obligation	14,333		0
Asset retirement obligations	4,513		6,283
Defined benefit pension obligations	1,821	[3]	1,763	[3]
Postretirement health care benefit obligations	2,634	[3]	3,022	[3]
Deferred compensation - SERP obligation and other	3,310	[1]	3,172	[1]
Other	2,290		1,647
Other liabilities	$ 28,901		$ 15,887

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

[2] Includes employer matching obligations under our defined contribution retirement plan of $0.2 million and $0.3 million as of December 31, 2012 and 2011, respectively. The expense recognized with respect to this plan was $0.9 million, $1.2 million and $1.7 million for the years ended December 31, 2012, 2011 and 2010, respectively.

[3] Includes the combined unfunded benefit obligations under our defined benefit pension and postretirement health care plans of $5.1 million and $5.4 million as of December 31, 2012 and 2011. The expense recognized with respect to these plans was $0.3 million, $0.4 million and $0.6 million for the years ended December 31, 2012, 2011 and 2010, respectively.