Earnings Per Share - Schedule of Calculations of Basic and Diluted EPS (Details) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024 USD ($) $ / shares shares	Sep. 30, 2023 USD ($) $ / shares shares	Sep. 30, 2024 USD ($) day $ / shares shares	Sep. 30, 2023 USD ($) $ / shares shares
Income Amounts Attributable to Parent, Disclosures [Abstract]
Net earnings attributable to Fluor | $	$ 54	$ 206	$ 282	$ 161
Less: Dividends on CPS | $	0	10	0	29
Less: Make-whole payment on conversion of CPS | $	0	27	0	27
Net earnings available to Fluor common stockholders, basic | $	$ 54	$ 169	$ 282	$ 105
Weighted average common shares outstanding (shares)	171,000,000	144,000,000	171,000,000	143,000,000
Diluted effect:
CPS (in shares)	0	0	0	0
Stock options, RSUs performance-based award units (in shares)	3,000,000	3,000,000	3,000,000	3,000,000
Convertible debt (in shares)	0	0	0	0
Weighted average diluted shares outstanding (in shares)	174,000,000	147,000,000	174,000,000	146,000,000
Basic EPS available to Fluor common stockholders (in dollars per share) | $ / shares	$ 0.32	$ 1.18	$ 1.65	$ 0.73
Diluted EPS available to Fluor common stockholders (in dollars per share) | $ / shares	$ 0.31	$ 1.15	1.63	$ 0.72
Additional shares to diluted shares outstanding during the quarter	484,208
2029 Notes (1.125% Convertible Senior Notes) | Convertible Debt
Diluted effect:
Conversion price (in dollars per share) | $ / shares	$ 45.37		45.37
Stock price trigger (in dollar per share) | $ / shares			$ 58.98
Weighted average share price (in dollars per share) | $ / shares	$ 47.17
2029 Notes (1.125% Convertible Senior Notes) | Convertible Debt | Debt Conversion Terms One
Diluted effect:
Threshold trading days | day			20
Threshold consecutive trading days | day			30