Postemployment Benefit Plans (Costs) (Details) $ in Millions	1 Months Ended		12 Months Ended
	Dec. 31, 2014 plan	Sep. 30, 2014 plan	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Net periodic benefit costs, before tax
Service cost			$ 13	$ 32
Interest cost			87	86
Net periodic benefit costs			11	26	$ 75
Unrecognized accumulated other comprehensive income, before tax
Actuarial loss, net			(413)	(406)
Prior service cost, net			26	31
Total			(387)	(375)
Accumulated other comprehensive income expected to be recognized during the next fiscal year
Actuarial loss, net			6
Prior service cost, net			(3)
Total amount expected to be recognized			3
Transocean Plans
Net periodic benefit costs, before tax
Service cost			13	31	68
Interest cost			86	84	91
Expected return on plan assets			(105)	(115)	(103)
Settlements and curtailments			(5)	5	(4)
Actuarial (gain) loss, net			4	22	22
Prior service cost, net					(1)
Net periodic benefit costs			(7)	27	73
U.S. Plans
Net periodic benefit costs, before tax
Service cost			3	5	39
Interest cost			69	65	64
Expected return on plan assets			(80)	(87)	(75)
Settlements and curtailments				3	(7)
Actuarial (gain) loss, net			5	11	17
Prior service cost, net					(1)
Net periodic benefit costs			(3)	(3)	37
Unrecognized accumulated other comprehensive income, before tax
Actuarial loss, net			(316)	(281)
Total			(316)	(281)
Accumulated other comprehensive income expected to be recognized during the next fiscal year
Actuarial loss, net			5
Total amount expected to be recognized			5
Non-U.S. Plans
Net periodic benefit costs, before tax
Service cost			10	26	29
Interest cost			17	19	27
Expected return on plan assets			(25)	(28)	(28)
Settlements and curtailments			(5)	2	3
Actuarial (gain) loss, net			(1)	11	5
Net periodic benefit costs			(4)	30	36
Number of unfunded defined plans that recognized settlement and curtailment charges | plan	2	2
Unrecognized accumulated other comprehensive income, before tax
Actuarial loss, net			(94)	(119)
Total			(94)	(119)
Accumulated other comprehensive income expected to be recognized during the next fiscal year
Actuarial loss, net			1
Total amount expected to be recognized			1
OPEB Plans
Net periodic benefit costs, before tax
Service cost				1
Interest cost			1	2
Net periodic benefit costs			(4)	(1)	$ 2
Unrecognized accumulated other comprehensive income, before tax
Actuarial loss, net			(3)	(6)
Prior service cost, net			26	31
Total			23	$ 25
Accumulated other comprehensive income expected to be recognized during the next fiscal year
Prior service cost, net			(3)
Total amount expected to be recognized			$ (3)