Annual report pursuant to Section 13 and 15(d)

Disposition of Assets - Additional Information (Detail)

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Disposition of Assets - Additional Information (Detail) (USD $)
1 Months Ended 12 Months Ended 3 Months Ended
Dec. 31, 2012
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2013
New Zealand [Member]
rig
Dec. 31, 2013
Oklahoma [Member]
Sep. 30, 2013
Mexico [Member]
Significant Acquisitions and Disposals [Line Items]              
Number of land rigs sold         2    
Assets held-for-sale, at carrying value         $ 2,300,000   $ 300,000
Asset dispositions, proceeds 200,000       3,200,000 800,000 500,000
Asset dispositions, loss 500,000   500,000   900,000 (100,000) 200,000
Provision for reduction in carrying value of certain assets   $ 2,544,000 $ 0 $ 1,350,000