Project Changes in Estimates - Additional Information (Detail) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018 USD ($) Project	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) Project	Sep. 30, 2017 USD ($)
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Effect of changes in estimated project cost on operating results		$ 36		$ 115
NCSA, MENA and APAC [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Effect of changes in estimated project cost on operating results	$ 79		$ 200
NCSA [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Effect of changes in estimated project cost on operating results	18		18
MENA [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Effect of changes in estimated project cost on operating results	$ 49	36	118	72
Number of projects | Project	3
APAC [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Effect of changes in estimated project cost on operating results	$ 9	$ 4	$ 64	$ 44
Number of projects | Project			2