Earnings Per Share - Schedule of Calculations of Basic and Diluted EPS (Details) $ / shares in Units, shares in Millions, $ in Millions	1 Months Ended	12 Months Ended
	Aug. 31, 2023 day $ / shares	Dec. 31, 2023 USD ($) day $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares
Net earnings (loss) from Cont Ops attributable to Fluor
Net earnings (loss) from Cont Ops attributable to Fluor | $		$ 139	$ 145	$ (405)
Less: Dividends on CPS | $		29	39	24
Less: Make-whole payment on conversion of CPS | $		27	0	0
Net earnings (loss) from Cont Ops available to Fluor common stockholders | $		83	106	(429)
Net earnings (loss) from Disc Ops attributable to Fluor | $		0	0	(35)
Net earnings (loss) available to Fluor common stockholders, basic | $		$ 83	$ 106	$ (464)
Weighted average common shares outstanding (in shares) | shares		150	142	141
Diluted effect:
CPS (in shares) | shares		0	0	0
Stock options, RSUs, restricted stock and performance-based award units (in shares) | shares		3	3	0
Convertible debt (in shares) | shares		0	0	0
Weighted average diluted shares outstanding (in shares) | shares		153	145	141
Basic EPS available to Fluor common stockholders:
Net earnings (loss) from Cont Ops (in dollars per share) | $ / shares		$ 0.55	$ 0.75	$ (3.04)
Net earnings (loss) from Disc Ops (in dollars per share) | $ / shares		0	0	(0.25)
Diluted EPS available to Fluor common stockholders:
Net earnings (loss) from Cont Ops (in dollars per share) | $ / shares		0.54	0.73	(3.04)
Net earnings (loss) from Disc Ops (in dollars per share) | $ / shares		0	$ 0	$ (0.25)
2029 Senior Notes | Convertible Debt
Diluted EPS available to Fluor common stockholders:
Conversion price (in dollars per share) | $ / shares	$ 45.37	45.37
Stock price trigger (in dollar per share) | $ / shares		$ 58.98
2029 Senior Notes | Convertible Debt | Debt Conversion Terms One
Diluted EPS available to Fluor common stockholders:
Threshold trading days | day	20	20
Threshold consecutive trading days | day		30