Segments and Geographic Area Analysis - Individual Countries that Comprised 5% or More of Our Total Contract Drilling Revenues from Unaffiliated Customers (Detail)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Brazil [Member]
Segment Reporting Information [Line Items]
Percentage of total drilling revenues from unaffiliated customers	46.10%	49.40%	36.80%
United Kingdom [Member]
Segment Reporting Information [Line Items]
Percentage of total drilling revenues from unaffiliated customers	6.90%	4.60%	5.60%
Australia [Member]
Segment Reporting Information [Line Items]
Percentage of total drilling revenues from unaffiliated customers	6.70%	6.70%	10.00%
Mexico [Member]
Segment Reporting Information [Line Items]
Percentage of total drilling revenues from unaffiliated customers	6.60%	1.90%	4.10%
Angola [Member]
Segment Reporting Information [Line Items]
Percentage of total drilling revenues from unaffiliated customers	2.70%	9.60%	6.10%
Indonesia [Member]
Segment Reporting Information [Line Items]
Percentage of total drilling revenues from unaffiliated customers	2.40%	5.00%	1.30%