Joint Venture and Consortium Arrangements - Summarized Balance Sheet Information for Consolidated Joint Ventures (Detail) $ in Millions	Sep. 30, 2018 USD ($)	[1]
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Current assets	$ 75
Non-current assets	15
Total assets	90
Current liabilities	$ 72

[1] All balances at September 30, 2018 resulted from the Combination and are subject to change when additional information is obtained during the measurement period.