Information about Operations in Different Segments (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2011
Exxon Mobil Corporation | Asia Pacific
Segment Reporting Information [Line Items]
Percentage of net revenue	36.00%
Chevron Corporation | Asia Pacific
Segment Reporting Information [Line Items]
Percentage of net revenue	10.00%
Saudi Aramco | Middle East
Segment Reporting Information [Line Items]
Percentage of net revenue	24.00%