Annual report pursuant to Section 13 and 15(d)

Revenues from Major Customers (Detail)

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Revenues from Major Customers (Detail) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2012
Chevron Corporation
Dec. 31, 2011
Chevron Corporation
Dec. 31, 2012
Williams Field Services-Gulf Coast Company L.P.
Dec. 31, 2010
Eni US Operating Co. Inc
Dec. 31, 2010
American Electric Power Service Corporation
Dec. 31, 2010
Versabuild, LLC
Revenue, Major Customer [Line Items]            
Revenue from major customer $ 192,370 $ 63,769 $ 124,841 $ 38,497 $ 27,858 $ 27,407