Drilling Fleet (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Changes in construction work in progress, including capital expenditures and other capital additions, such as capitalized interest
Total capital expenditures	$ 153	$ 138
Construction in Progress
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	753	632
Total capital expenditures	153	138
Changes in accrued capital additions	(31)	21
Property and equipment placed into service	(98)	(76)
Construction work in progress, at end of period	777	715
New builds
Changes in construction work in progress, including capital expenditures and other capital additions, such as capitalized interest
Total capital expenditures	70	41
Other property and equipment
Changes in construction work in progress, including capital expenditures and other capital additions, such as capitalized interest
Total capital expenditures	$ 83	$ 97