Suspended Exploratory Well Costs - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified			3 Months Ended
	Sep. 30, 2013 Well	Dec. 31, 2012	Mar. 31, 2012 East Texas
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Capitalized exploratory well costs that have been capitalized for a period greater than one year	$ 12,880	$ 11,395
Number of wells waiting on pipeline	2
Number of wells in completion stage	2
Number of wells not operated	1
Sale of oil and gas properties			75.00%