Use of Estimates - Additional Information (Detail) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) Project	Sep. 30, 2016 USD ($) Project	Dec. 31, 2016 USD ($)
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Effect of changes in estimated project cost on operating results	$ 36	$ 34		$ 101
AEA [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Effect of changes in estimated project cost on operating results	4	6	$ (3)	$ 29
Number of projects | Project				2
AEA [Member] | PB Litoral project [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Effect of changes in estimated project cost on operating results				$ 7
MEA [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Effect of changes in estimated project cost on operating results	36	12	$ 72	29
Number of projects | Project			2
ASA [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Effect of changes in estimated project cost on operating results	$ 4	$ 16	$ 46	$ 43
ASA [Member] | Ichthys Project [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Effect of changes in estimated project cost on operating results					$ 34
ASA [Member] | Ichthys Project [Member] | Maximum [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Effect of additional estimated project costs On Income					$ 10
MEA and ASA Segments [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Effect of changes in estimated project cost on operating results			$ 115