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Partnerships and Joint Ventures - Ownership and Receivables (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2020	Dec. 31, 2019
COOEC Fluor Heavy Industries Co., Ltd.
Variable interest entity information
Commitment amount	$ 26		$ 26
Unconsolidated variable interest entities \| Accounts and notes receivable, net
Variable interest entity information
Receivables related to work performed for unconsolidated partnerships and joint ventures	175		175	$ 149
Energy Chemicals And Mining Segment
Variable interest entity information
Impairment of equity method investments		$ 86	$ 86
COOEC Fluor Heavy Industries Co., Ltd.
Variable interest entity information
Ownership percentage			49.00%
Discontinued Operations, Disposed of by Sale \| SACYR \| Energy & Chemicals
Variable interest entity information
Ownership percentage			50.00%
Loss on sale of investment	$ 11
Partnership \| Minority Interest Ownership Percentage by Parent \| Majority
Variable interest entity information
Entity's interest in partnership or joint venture (as a percent)	50.00%		50.00%