Summary of Accounts Receivable (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Receivables [Abstract]
Customers	$ 93,288	$ 43,967
Joint interest partners	76,199	16,154
Other	25,538	4,523
Accounts Receivable, Gross, Current, Total	195,025	64,644
Less: Allowance for doubtful accounts	(622)	(1,666)
Accounts receivable, net of allowance for doubtful accounts	$ 194,403	$ 62,978