Segments and Geographic Area Analysis - Revenues from Contract Drilling Services by Equipment Type (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Segment Reporting Information [Line Items]
Contract drilling	$ 690,741	$ 714,027	$ 2,135,612	$ 2,195,443
Revenues related to reimbursable expenses	15,424	15,114	58,312	40,528
Total revenues	706,165	729,141	2,193,924	2,235,971
Ultra-deepwater semisubmersible [Member]
Segment Reporting Information [Line Items]
Contract drilling	195,215	195,574	617,673	673,233
Deepwater [Member]
Segment Reporting Information [Line Items]
Contract drilling	147,333	163,816	495,858	452,384
Mid-Water [Member]
Segment Reporting Information [Line Items]
Contract drilling	297,368	319,491	891,449	948,548
Total Floaters [Member]
Segment Reporting Information [Line Items]
Contract drilling	639,916	678,881	2,004,980	2,074,165
Jack-Ups [Member]
Segment Reporting Information [Line Items]
Contract drilling	$ 50,825	$ 35,146	$ 130,632	$ 121,278