Reconciliation of Asset Retirement Obligations which are Included in Other Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of year	$ 4,513		$ 6,283
Liabilities incurred	1,675	[1]	57	[1]
Liabilities settled	(220)		(236)
Sale of properties	0		(1,976)
Accretion expense	469		385
Balance at end of year	6,437		4,513
Eagle Ford Shale
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Liabilities incurred	$ 1,500

[1] Includes $1.5 million recognized in connection with the 2013 EF Acquisition.