Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Net earnings (loss) from Cont Ops attributable to Fluor
Net earnings (loss) attributable to Fluor Corporation from Cont Ops	$ (161,000)	$ 46,000	$ (6,000)	$ (61,000)	$ (107,000)	$ 21,000	$ (15,000)	$ 22,000	$ (181,736)	$ (79,079)	$ (1,282,642)
Less: Dividends on CPS									24,375	0	0
Net earnings (loss) from Cont Ops available to Fluor common stockholders									(206,111)	(79,079)	(1,282,642)
Net earnings (loss) from Disc Ops attributable to Fluor	$ (118,000)	$ (6,000)	$ (108,000)	$ (26,000)	$ (56,000)	$ (2,000)	$ (10,000)	$ (288,000)	(258,434)	(355,967)	(239,522)
Net earnings (loss) available to Fluor common stockholders									$ (464,545)	$ (435,046)	$ (1,522,164)
Weighted average common shares outstanding (shares)									141,275	140,511	140,061
Diluted effect:
CPS (in shares)									0	0	0
Stock options, RSU's, restricted stock and performance-based award units (in shares)									0	0	0
Weighted average diluted shares outstanding (in shares)									141,275	140,511	140,061
Basic EPS available to Fluor common stockholders:
Net earnings (loss) from continuing operations (in dollars per share)	$ (1.21)	$ 0.26	$ (0.08)	$ (0.43)	$ (0.76)	$ 0.15	$ (0.11)	$ 0.15	$ (1.46)	$ (0.56)	$ (9.16)
Net earnings (loss) from Disc Ops (in dollars per share)	(0.84)	(0.04)	(0.76)	(0.19)	(0.40)	(0.01)	(0.07)	(2.05)	(1.83)	(2.53)	(1.71)
Diluted EPS available to Fluor common stockholders:
Net earnings (loss) from continuing operations (in dollars per share)	(1.21)	0.26	(0.08)	(0.43)	(0.76)	0.15	(0.11)	0.15	(1.46)	(0.56)	(9.16)
Net earnings from discontinued operations (in dollars per share)	$ (0.84)	$ (0.04)	$ (0.76)	$ (0.19)	$ (0.40)	$ (0.01)	$ (0.07)	$ (2.05)	$ (1.83)	$ (2.53)	$ (1.71)