Drilling Fleet (Details 3) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended	12 Months Ended
	Jun. 30, 2010	Dec. 31, 2011	Dec. 31, 2010 drillingunit	Dec. 31, 2009
Dispositions
Net cash proceeds from sale of assets		$ 177	$ 60	$ 18
Gain (loss) on the sale of assets		4	257	(9)
Number of Midwater Floaters sold (in drilling units)			2
Unconsolidated affiliates
Net gain on sale of ownership interest				30
Net gain on sale of ownership interest per diluted share				$ 0.09
Loss of drilling unit
Proceeds from insurance recoveries for loss of drilling unit			560
Gain on loss of drilling unit	267		267
Gain loss on loss of drilling unit per diluted share			$ 0.83
Drilling and Oil Transportation Equipment
Dispositions
Net cash proceeds from sale of assets		163
Gain (loss) on the sale of assets		19
Gain (loss) on the sale of assets per diluted share		$ 0.06
Recognized gain (loss) on disposal of unrelated assets		(15)
Midwater Floaters
Dispositions
Net cash proceeds from sale of assets			38
Gain (loss) on the sale of assets			(15)
Gain (loss) on the sale of assets per diluted share			$ 0.04
Recognized gain (loss) on disposal of unrelated assets			5
Number of Midwater Floaters sold (in drilling units)			2
Number of notes receivable provided as Non-Cash proceeds from sale of assets			2
Non-cash proceeds in the form of notes receivable from sale of assets			165
Sale of Sedco 135-D
Dispositions
Net cash proceeds from sale of assets				18
Gain (loss) on the sale of assets				(9)
Gain (loss) on the sale of assets per diluted share				$ 0.03
Caspian Drilling Company Limited
Unconsolidated affiliates
Ownership interest in affiliate (as a percent)				45.00%
Net proceeds received for the exchange of ownership interest				4
Arab Drilling & Workover Company
Unconsolidated affiliates
Ownership interest in affiliate (as a percent)				40.00%
Net proceeds received for the exchange of ownership interest				38
Overseas Drilling Limited
Unconsolidated affiliates
Ownership interest in affiliate (as a percent)		50.00%
Net proceeds received for the exchange of ownership interest		22
Net gain on sale of ownership interest		$ 13
Net gain on sale of ownership interest per diluted share		$ 0.04