Postemployment Benefit Plans (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Fair value of plan assets
Total investments	$ 1,120	$ 1,029	$ 875
Transocean Plans
Fair value of plan assets
Total investments	1,120	1,029
Transocean Plans | Significant observable inputs
Fair value of plan assets
Total investments	805	726
Transocean Plans | Significant other observable inputs
Fair value of plan assets
Total investments	315	303
Transocean Plans | Equity securities
Fair value of plan assets
Total investments	654	628
Transocean Plans | Equity securities | Significant observable inputs
Fair value of plan assets
Total investments	486	450
Transocean Plans | Equity securities | Significant other observable inputs
Fair value of plan assets
Total investments	168	178
Transocean Plans | U.S. equity securities
Fair value of plan assets
Total investments	424	387
Transocean Plans | U.S. equity securities | Significant observable inputs
Fair value of plan assets
Total investments	395	359
Transocean Plans | U.S. equity securities | Significant other observable inputs
Fair value of plan assets
Total investments	29	28
Transocean Plans | Non-U.S. equity securities
Fair value of plan assets
Total investments	230	241
Transocean Plans | Non-U.S. equity securities | Significant observable inputs
Fair value of plan assets
Total investments	91	91
Transocean Plans | Non-U.S. equity securities | Significant other observable inputs
Fair value of plan assets
Total investments	139	150
Transocean Plans | Fixed income securities
Fair value of plan assets
Total investments	321	275
Transocean Plans | Fixed income securities | Significant observable inputs
Fair value of plan assets
Total investments	278	241
Transocean Plans | Fixed income securities | Significant other observable inputs
Fair value of plan assets
Total investments	43	34
Transocean Plans | U.S. government
Fair value of plan assets
Total investments	52	59
Transocean Plans | U.S. government | Significant observable inputs
Fair value of plan assets
Total investments	52	59
Transocean Plans | U.S. corporate
Fair value of plan assets
Total investments	9	175
Transocean Plans | U.S. corporate | Significant observable inputs
Fair value of plan assets
Total investments	9	175
Transocean Plans | Non U.S. government
Fair value of plan assets
Total investments	221	34
Transocean Plans | Non U.S. government | Significant observable inputs
Fair value of plan assets
Total investments	178
Transocean Plans | Non U.S. government | Significant other observable inputs
Fair value of plan assets
Total investments	43	34
Transocean Plans | Non U.S. corporate
Fair value of plan assets
Total investments	39	7
Transocean Plans | Non U.S. corporate | Significant observable inputs
Fair value of plan assets
Total investments	39	7
Transocean Plans | Other investments
Fair value of plan assets
Total investments	145	126
Transocean Plans | Other investments | Significant observable inputs
Fair value of plan assets
Total investments	41	35
Transocean Plans | Other investments | Significant other observable inputs
Fair value of plan assets
Total investments	104	91
Transocean Plans | Cash
Fair value of plan assets
Total investments	41	35
Transocean Plans | Cash | Significant observable inputs
Fair value of plan assets
Total investments	41	35
Transocean Plans | Property
Fair value of plan assets
Total investments	8	7
Transocean Plans | Property | Significant other observable inputs
Fair value of plan assets
Total investments	8	7
Transocean Plans | Investment contracts
Fair value of plan assets
Total investments	96	84
Transocean Plans | Investment contracts | Significant other observable inputs
Fair value of plan assets
Total investments	96	84
U.S. Plans
Weighted-average target allocations of the investments
Target allocation percentage, equity securities	65.00%
Target allocation percentage, fixed income securities	35.00%
Total target allocation percentage	100.00%
Weighted-average actual allocations of the investments
Actual allocation percentage, equity securities	64.00%	65.00%
Actual allocation percentage, fixed income securities	36.00%	34.00%
Actual allocation percentage, other investments		1.00%
Total actual allocation percentage	100.00%	100.00%
Fair value of plan assets
Total investments	769	697	594
U.S. Plans | Significant observable inputs
Fair value of plan assets
Total investments	767	695
U.S. Plans | Significant other observable inputs
Fair value of plan assets
Total investments	2	2
U.S. Plans | Equity securities
Fair value of plan assets
Total investments	488	452
U.S. Plans | Equity securities | Significant observable inputs
Fair value of plan assets
Total investments	486	450
U.S. Plans | Equity securities | Significant other observable inputs
Fair value of plan assets
Total investments	2	2
U.S. Plans | U.S. equity securities
Fair value of plan assets
Total investments	395	359
U.S. Plans | U.S. equity securities | Significant observable inputs
Fair value of plan assets
Total investments	395	359
U.S. Plans | Non-U.S. equity securities
Fair value of plan assets
Total investments	93	93
U.S. Plans | Non-U.S. equity securities | Significant observable inputs
Fair value of plan assets
Total investments	91	91
U.S. Plans | Non-U.S. equity securities | Significant other observable inputs
Fair value of plan assets
Total investments	2	2
U.S. Plans | Fixed income securities
Fair value of plan assets
Total investments	278	241
U.S. Plans | Fixed income securities | Significant observable inputs
Fair value of plan assets
Total investments	278	241
U.S. Plans | U.S. government
Fair value of plan assets
Total investments	52	59
U.S. Plans | U.S. government | Significant observable inputs
Fair value of plan assets
Total investments	52	59
U.S. Plans | U.S. corporate
Fair value of plan assets
Total investments	9	175
U.S. Plans | U.S. corporate | Significant observable inputs
Fair value of plan assets
Total investments	9	175
U.S. Plans | Non U.S. government
Fair value of plan assets
Total investments	178
U.S. Plans | Non U.S. government | Significant observable inputs
Fair value of plan assets
Total investments	178
U.S. Plans | Non U.S. corporate
Fair value of plan assets
Total investments	39	7
U.S. Plans | Non U.S. corporate | Significant observable inputs
Fair value of plan assets
Total investments	39	7
U.S. Plans | Other investments
Fair value of plan assets
Total investments	3	4
U.S. Plans | Other investments | Significant observable inputs
Fair value of plan assets
Total investments	3	4
U.S. Plans | Cash
Fair value of plan assets
Total investments	3	4
U.S. Plans | Cash | Significant observable inputs
Fair value of plan assets
Total investments	3	4
Non-U.S. Plans
Weighted-average target allocations of the investments
Target allocation percentage, equity securities	51.00%
Target allocation percentage, fixed income securities	14.00%
Target allocation percentage, other investments	35.00%
Total target allocation percentage	100.00%
Weighted-average actual allocations of the investments
Actual allocation percentage, equity securities	47.00%	53.00%
Actual allocation percentage, fixed income securities	12.00%	10.00%
Actual allocation percentage, other investments	41.00%	37.00%
Total actual allocation percentage	100.00%	100.00%
Fair value of plan assets
Total investments	351	332	281
Non-U.S. Plans | Significant observable inputs
Fair value of plan assets
Total investments	38	31
Non-U.S. Plans | Significant other observable inputs
Fair value of plan assets
Total investments	313	301
Non-U.S. Plans | Equity securities
Fair value of plan assets
Total investments	166	176
Non-U.S. Plans | Equity securities | Significant other observable inputs
Fair value of plan assets
Total investments	166	176
Non-U.S. Plans | U.S. equity securities
Fair value of plan assets
Total investments	29	28
Non-U.S. Plans | U.S. equity securities | Significant other observable inputs
Fair value of plan assets
Total investments	29	28
Non-U.S. Plans | Non-U.S. equity securities
Fair value of plan assets
Total investments	137	148
Non-U.S. Plans | Non-U.S. equity securities | Significant other observable inputs
Fair value of plan assets
Total investments	137	148
Non-U.S. Plans | Fixed income securities
Fair value of plan assets
Total investments	43	34
Non-U.S. Plans | Fixed income securities | Significant other observable inputs
Fair value of plan assets
Total investments	43	34
Non-U.S. Plans | Non U.S. government
Fair value of plan assets
Total investments	43	34
Non-U.S. Plans | Non U.S. government | Significant other observable inputs
Fair value of plan assets
Total investments	43	34
Non-U.S. Plans | Other investments
Fair value of plan assets
Total investments	142	122
Non-U.S. Plans | Other investments | Significant observable inputs
Fair value of plan assets
Total investments	38	31
Non-U.S. Plans | Other investments | Significant other observable inputs
Fair value of plan assets
Total investments	104	91
Non-U.S. Plans | Cash
Fair value of plan assets
Total investments	38	31
Non-U.S. Plans | Cash | Significant observable inputs
Fair value of plan assets
Total investments	38	31
Non-U.S. Plans | Property
Fair value of plan assets
Total investments	8	7
Non-U.S. Plans | Property | Significant other observable inputs
Fair value of plan assets
Total investments	8	7
Non-U.S. Plans | Investment contracts
Fair value of plan assets
Total investments	96	84
Non-U.S. Plans | Investment contracts | Significant other observable inputs
Fair value of plan assets
Total investments	$ 96	$ 84