Segments and Geographic Area Analysis - Revenues from Major Customers that Contributed More than 10% of Total Revenues (Detail)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Petroleo Brasileiro S.A. [Member]
Revenue, Major Customer [Line Items]
Percentage of revenues from major customers	33.30%	35.00%	23.70%
OGX Petroleo e Gas Ltda [Member]
Revenue, Major Customer [Line Items]
Percentage of revenues from major customers	12.50%	14.10%	14.10%