Segment Reporting - Information about Operations in Different Segments (Parenthetical) (Detail) - USD ($) $ in Millions	1 Months Ended	6 Months Ended
Jan. 31, 2017	Jun. 30, 2017	Jun. 30, 2016
Amazon Pipelay and Construction Vessel [Member]
Segment Reporting Information [Line Items]
Bareboat charter agreement, term	11 years	11 years
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Gain on sale of assets		$ 3	$ 3
Asset Impairment Charges		$ 32	$ 32

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=68055307&loc=d3e2420-110228

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585

Name:	us-gaap_AssetImpairmentCharges
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration