Basis of Presentation and Significant Accounting Policies - Components of Inventories (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Accounting Policies [Abstract]
Tubular goods and equipment	$ 13,586	$ 11,139
Crude oil	68,978	43,301
Total	$ 82,564	$ 54,440