Components of Selected Balance Sheet Accounts (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Other current assets:
Tubular inventory and well materials	$ 5,323	$ 5,802
Prepaid expenses	4,267	4,215
Other Assets, Miscellaneous, Current	97	97
Other Assets, Current	9,687	10,114
Other assets:
Assets of supplemental employee retirement plan (“SERP”)	4,216	4,123
Other	95	95
Other assets	4,311	4,218
Accounts payable and accrued liabilities:
Trade accounts payable	121,891	174,496
Drilling and other lease operating costs	47,131	68,842
Royalties	25,971	27,883
Compensation – related	4,313	9,197
Interest	37,630	15,555
Preferred stock dividends	6,067	6,067
Other	2,063	10,187
Accounts payable and accrued liabilities	245,066	312,227
Other liabilities:
Deferred gains on sale of assets	90,463	90,569
Firm transportation obligation	11,723	12,042
Asset retirement obligations (“AROs”)	6,049	5,889
Defined benefit pension obligations	1,565	1,753
Postretirement health care benefit obligations	914	890
Compensation-related	7,612	7,631
Deferred compensation – SERP obligations and other	4,270	4,183
Other	928	929
Other liabilities	$ 123,524	$ 123,886