Accounts Receivable - Trade Accounts Receivable Balances (Detail) - USD ($) $ in Millions		Sep. 30, 2018	Dec. 31, 2017
Accounts Notes And Loans Receivable [Line Items]
Contract receivables	[1]	$ 965	$ 225
Retainages	[2]	145	120
Accounts receivable—trade, net		1,093	328
Contract receivables [Member]
Accounts Notes And Loans Receivable [Line Items]
Less allowances		(17)	(17)
Accounts receivable—trade, net		$ 1,093	$ 328

[1] Unbilled receivables for our performance obligations recognized at a point in time are recorded within accounts receivable and were approximately $32 million at September 30, 2018 (all resulted from the acquired CB&I operations).

[2] Retainages classified within Accounts receivable-trade, net are anticipated to be collected within one year. Retainages anticipated to be collected beyond one year are classified as Accounts receivable long-term retainages on our Balance Sheet.