Organization and Significant Accounting Policies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014 JointVenture Rigs	Dec. 31, 2013	Dec. 31, 2012
Description Of Business And Basis Of Presentation [Line Items]
Number of semisubmersibles	8
Number of drillships	9
Number of jackups	15
Number of harsh environment jackup rigs under construction	1
Share exchanged for each ordinary shares	1
Number of joint ventures, where the company hold the variable interest	2
Percentage of variable interest in joint ventures	50.00%
Maturity period of highly liquid investments	Three months or less
Capital accruals	$ 70	$ 88
Period for incurring maintenance costs, Minimum	3 years
Period for incurring maintenance costs, Maximum	5 years
Deferred costs for major maintenance projects, net of accumulated depreciation	179	400
Depreciation expense related to overhauls and asset replacement	77	70	53
Loss reserves for personal injury and protection claims	21	29
Deferred revenues under drilling contracts	263	303
Deferred expenses under drilling contracts	$ 94	$ 157
Drilling Equipment [Member] | Minimum [Member]
Description Of Business And Basis Of Presentation [Line Items]
Maximum useful life of property plant and equipment	3 years
Drilling Equipment [Member] | Maximum [Member]
Description Of Business And Basis Of Presentation [Line Items]
Maximum useful life of property plant and equipment	30 years
Other [Member] | Minimum [Member]
Description Of Business And Basis Of Presentation [Line Items]
Maximum useful life of property plant and equipment	2 years
Other [Member] | Maximum [Member]
Description Of Business And Basis Of Presentation [Line Items]
Maximum useful life of property plant and equipment	40 years