Drilling Fleet (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Changes in construction work in progress, including capital expenditures and other capital additions, such as capitalized interest
Construction work in progress, at beginning of period	$ 3,735	$ 2,447	$ 2,708
Total capital expenditures	1,344	2,001	2,165
Changes in accrued capital additions	(86)	(11)	(45)
Impairment of construction work in progress		(52)
Construction work in progress, at end of period	2,171	3,735	2,447
New builds
Changes in construction work in progress, including capital expenditures and other capital additions, such as capitalized interest
Total capital expenditures	1,206	1,622	1,436
Property and equipment placed into service	(2,557)		(1,522)
Other equipment and construction projects
Changes in construction work in progress, including capital expenditures and other capital additions, such as capitalized interest
Total capital expenditures	138	379	729
Other property and equipment
Changes in construction work in progress, including capital expenditures and other capital additions, such as capitalized interest
Property and equipment placed into service	$ (265)	$ (650)	$ (859)