Significant Accounting Policies (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 Y D M	Dec. 31, 2010	Dec. 31, 2009
Significant Accounting Policies
Equity in earnings of unconsolidated affiliates	$ 18	$ 8	$ 6
Carrying amounts of investments in and advances to unconsolidated affiliates	1	19
Business combination
Period from date of acquisition for completion of assessments of fair values of acquired assets and liabilities (in years)	1
Contract drilling intangible revenues
Contract drilling intangible revenues	45	98	281
Share-based compensation expense
Number of trading days considered for calculation of average stock price	30
Share-based compensation expense	95	102	81
Income tax benefit on share-based compensation expense	16	13	11
Capitalized interest
Capitalized interest costs on construction work in progress	39	89	182
Foreign currency
Net foreign currency exchange loss	(99)	1	(33)
Cash and cash equivalents
Maximum period within which restriction is expected to expire for classifying restricted cash and investment as current assets (in years)	1
Minimum period after which restriction is expected to expire for classifying restricted cash and investment as other assets (in years)	1
Maximum term of original maturity to classify instruments as cash and cash equivalents (in months)	3
Restricted cash investments	928	47
Restricted cash investments classified in other current assets	182
Restricted cash investments classified in other assets	746
Allowance for doubtful accounts
Allowance for doubtful accounts	28	38
Materials and supplies
Allowance for obsolescence on materials and supplies	73	70
Assets held for sale
Assets held for sale, maximum		1
Assets held for sale, included in current assets	26
Property and equipment
Property and equipment as a percentage of total assets (as a percent)	64.00%
Depreciation and Amortization	(1,449)	(1,536)	(1,433)
Earnings (loss) from continuing operations (in dollars per share)	$ (18.40)	$ 2.88	$ 9.92
Drilling rig units
Property and equipment
Number of rigs for which useful life was adjusted	2	5	10
Drilling rig units | Service life
Property and equipment
Depreciation and Amortization	$ 2	$ 23	$ 23
Earnings (loss) from continuing operations (in dollars per share)	$ (0.01)	$ (0.07)	$ (0.07)
Drilling rig units | Maximum
Property and equipment
Estimated original useful life (in years)	35
Estimated useful life before adjustment (in years)	30	36	35
Estimated useful life after adjustment (in years)	38	39	50
Drilling rig units | Minimum
Property and equipment
Estimated original useful life (in years)	18
Estimated useful life before adjustment (in years)	20	20	30
Estimated useful life after adjustment (in years)	23	25	33
Buildings and improvements | Maximum
Property and equipment
Estimated original useful life (in years)	30
Buildings and improvements | Minimum
Property and equipment
Estimated original useful life (in years)	10
Machinery and equipment | Maximum
Property and equipment
Estimated original useful life (in years)	12
Machinery and equipment | Minimum
Property and equipment
Estimated original useful life (in years)	4