Postemployment Benefit Plans (Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Fair value of plan assets
Total investments	$ 2,055	$ 1,985	$ 1,799
Funding contributions
Employer contributions	10	$ 14	22
Expected defined plan contributions next year	4
Projected pension benefits payments
2022	91
2023	92
2024	92
2025	93
2026	93
2027-2031	$ 477
U.S.
Weighted-average target allocations of the investments
Total target allocation percentage	100.00%	100.00%
Total actual allocation percentage	100.00%	100.00%
U.S. | Equity securities
Weighted-average target allocations of the investments
Total target allocation percentage	38.00%	50.00%
Total actual allocation percentage	38.00%	55.00%
U.S. | Fixed income securities
Weighted-average target allocations of the investments
Total target allocation percentage	62.00%	50.00%
Total actual allocation percentage	62.00%	45.00%
Non-U.S. Plans
Weighted-average target allocations of the investments
Total target allocation percentage	100.00%	100.00%
Total actual allocation percentage	100.00%	100.00%
Non-U.S. Plans | Equity securities
Weighted-average target allocations of the investments
Total target allocation percentage	19.00%	27.00%
Total actual allocation percentage	19.00%	25.00%
Non-U.S. Plans | Fixed income securities
Weighted-average target allocations of the investments
Total target allocation percentage	81.00%	73.00%
Total actual allocation percentage	80.00%	74.00%
Non-U.S. Plans | Other investments
Weighted-average target allocations of the investments
Total actual allocation percentage	1.00%	1.00%
Transocean Plans
Fair value of plan assets
Total investments	$ 2,055	$ 1,985
Funding contributions
Expected defined plan contributions next year	1
Transocean Plans | Significant observable inputs
Fair value of plan assets
Total investments	1,613	1,560
Transocean Plans | Significant other observable inputs
Fair value of plan assets
Total investments	442	425
Transocean Plans | Mutual funds
Fair value of plan assets
Total investments	2,046	1,972
Transocean Plans | Mutual funds | Significant observable inputs
Fair value of plan assets
Total investments	1,604	1,548
Transocean Plans | Mutual funds | Significant other observable inputs
Fair value of plan assets
Total investments	442	424
Transocean Plans | U.S. equity funds
Fair value of plan assets
Total investments	421	586
Transocean Plans | U.S. equity funds | Significant observable inputs
Fair value of plan assets
Total investments	421	586
Transocean Plans | Non-U.S. equity funds
Fair value of plan assets
Total investments	276	373
Transocean Plans | Non-U.S. equity funds | Significant observable inputs
Fair value of plan assets
Total investments	184	263
Transocean Plans | Non-U.S. equity funds | Significant other observable inputs
Fair value of plan assets
Total investments	92	110
Transocean Plans | Bond funds
Fair value of plan assets
Total investments	1,349	1,013
Transocean Plans | Bond funds | Significant observable inputs
Fair value of plan assets
Total investments	999	699
Transocean Plans | Bond funds | Significant other observable inputs
Fair value of plan assets
Total investments	350	314
Transocean Plans | Other investments
Fair value of plan assets
Total investments		13
Transocean Plans | Other investments | Significant observable inputs
Fair value of plan assets
Total investments		12
Transocean Plans | Other investments | Significant other observable inputs
Fair value of plan assets
Total investments		1
Transocean Plans | Cash and money market funds
Fair value of plan assets
Total investments	9	12
Transocean Plans | Cash and money market funds | Significant observable inputs
Fair value of plan assets
Total investments	9	12
Transocean Plans | Investment contracts
Fair value of plan assets
Total investments		1
Transocean Plans | Investment contracts | Significant other observable inputs
Fair value of plan assets
Total investments		1
Transocean Plans | U.S.
Fair value of plan assets
Total investments	1,621	1,565	1,369
Funding contributions
Employer contributions	1	3
Projected pension benefits payments
2022	82
2023	83
2024	83
2025	84
2026	84
2027-2031	424
Transocean Plans | U.S. | Significant observable inputs
Fair value of plan assets
Total investments	1,610	1,554
Transocean Plans | U.S. | Significant other observable inputs
Fair value of plan assets
Total investments	11	11
Transocean Plans | U.S. | Mutual funds
Fair value of plan assets
Total investments	1,615	1,559
Transocean Plans | U.S. | Mutual funds | Significant observable inputs
Fair value of plan assets
Total investments	1,604	1,548
Transocean Plans | U.S. | Mutual funds | Significant other observable inputs
Fair value of plan assets
Total investments	11	11
Transocean Plans | U.S. | U.S. equity funds
Fair value of plan assets
Total investments	421	586
Transocean Plans | U.S. | U.S. equity funds | Significant observable inputs
Fair value of plan assets
Total investments	421	586
Transocean Plans | U.S. | Non-U.S. equity funds
Fair value of plan assets
Total investments	191	270
Transocean Plans | U.S. | Non-U.S. equity funds | Significant observable inputs
Fair value of plan assets
Total investments	184	263
Transocean Plans | U.S. | Non-U.S. equity funds | Significant other observable inputs
Fair value of plan assets
Total investments	7	7
Transocean Plans | U.S. | Bond funds
Fair value of plan assets
Total investments	1,003	703
Transocean Plans | U.S. | Bond funds | Significant observable inputs
Fair value of plan assets
Total investments	999	699
Transocean Plans | U.S. | Bond funds | Significant other observable inputs
Fair value of plan assets
Total investments	4	4
Transocean Plans | U.S. | Other investments
Fair value of plan assets
Total investments		6
Transocean Plans | U.S. | Other investments | Significant observable inputs
Fair value of plan assets
Total investments		6
Transocean Plans | U.S. | Cash and money market funds
Fair value of plan assets
Total investments	6	6
Transocean Plans | U.S. | Cash and money market funds | Significant observable inputs
Fair value of plan assets
Total investments	6	6
Transocean Plans | Non-U.S. Plans
Fair value of plan assets
Total investments	434	420	$ 430
Funding contributions
Employer contributions	7	9
Projected pension benefits payments
2022	6
2023	6
2024	6
2025	7
2026	8
2027-2031	52
Transocean Plans | Non-U.S. Plans | Significant observable inputs
Fair value of plan assets
Total investments	3	6
Transocean Plans | Non-U.S. Plans | Significant other observable inputs
Fair value of plan assets
Total investments	431	414
Transocean Plans | Non-U.S. Plans | Mutual funds
Fair value of plan assets
Total investments	431	413
Transocean Plans | Non-U.S. Plans | Mutual funds | Significant other observable inputs
Fair value of plan assets
Total investments	431	413
Transocean Plans | Non-U.S. Plans | Non-U.S. equity funds
Fair value of plan assets
Total investments	85	103
Transocean Plans | Non-U.S. Plans | Non-U.S. equity funds | Significant other observable inputs
Fair value of plan assets
Total investments	85	103
Transocean Plans | Non-U.S. Plans | Bond funds
Fair value of plan assets
Total investments	346	310
Transocean Plans | Non-U.S. Plans | Bond funds | Significant other observable inputs
Fair value of plan assets
Total investments	346	310
Transocean Plans | Non-U.S. Plans | Other investments
Fair value of plan assets
Total investments		7
Transocean Plans | Non-U.S. Plans | Other investments | Significant observable inputs
Fair value of plan assets
Total investments		6
Transocean Plans | Non-U.S. Plans | Other investments | Significant other observable inputs
Fair value of plan assets
Total investments		1
Transocean Plans | Non-U.S. Plans | Cash and money market funds
Fair value of plan assets
Total investments	3	6
Transocean Plans | Non-U.S. Plans | Cash and money market funds | Significant observable inputs
Fair value of plan assets
Total investments	3	6
Transocean Plans | Non-U.S. Plans | Investment contracts
Fair value of plan assets
Total investments		1
Transocean Plans | Non-U.S. Plans | Investment contracts | Significant other observable inputs
Fair value of plan assets
Total investments		1
OPEB Plans
Funding contributions
Employer contributions	2	$ 2
Expected defined plan contributions next year	3
Projected pension benefits payments
2022	3
2023	3
2024	3
2025	2
2026	1
2027-2031	$ 1