Other Comprehensive Income (Loss) - Changes in AOCI Balances by Component (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Beginning balance	$ 1,263,227	$ 1,584,092	$ 2,980,253
Total OCI, net of tax	52,501	(36,150)	162,308
Ending balance	1,566,681	1,263,227	1,584,092
Other comprehensive income (loss) attributable to Fluor Corporation
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Beginning balance	(416,906)	(379,873)	(543,531)
OCI before reclassifications	(80,756)	(40,506)	13,162
Amounts reclassified from AOCI	131,923	3,473	150,496
Total OCI, net of tax	51,167	(37,033)	163,658
Ending balance	(365,739)	(416,906)	(379,873)
Foreign Currency Translation
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Beginning balance	(260,960)	(242,950)	(309,800)
OCI before reclassifications	(38,767)	(18,010)	19,957
Amounts reclassified from AOCI	0	0	46,893
Total OCI, net of tax	(38,767)	(18,010)	66,850
Ending balance	(299,727)	(260,960)	(242,950)
Ownership Share of Equity Method Investees' OCI
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Beginning balance	(53,984)	(35,456)	(23,672)
OCI before reclassifications	(2,259)	(19,076)	(12,304)
Amounts reclassified from AOCI	567	548	520
Total OCI, net of tax	(1,692)	(18,528)	(11,784)
Ending balance	(55,676)	(53,984)	(35,456)
DB Plans
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Beginning balance	(118,589)	(99,197)	(204,649)
OCI before reclassifications	(50,482)	(22,921)	4,006
Amounts reclassified from AOCI	151,454	3,529	101,446
Total OCI, net of tax	100,972	(19,392)	105,452
Ending balance	(17,617)	(118,589)	(99,197)
Unrealized Gain (Loss) on Hedges
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Beginning balance	16,627	(2,270)	(5,410)
OCI before reclassifications	10,752	19,501	1,503
Amounts reclassified from AOCI	(20,098)	(604)	1,637
Total OCI, net of tax	(9,346)	18,897	3,140
Ending balance	7,281	16,627	(2,270)
Less: OCI attributable to NCI
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Beginning balance	(4,168)	(5,051)	(3,701)
OCI before reclassifications	1,334	883	(1,350)
Amounts reclassified from AOCI	0	0	0
Total OCI, net of tax	1,334	883	(1,350)
Ending balance	(2,834)	(4,168)	(5,051)
Foreign Currency Translation
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Beginning balance	(4,168)	(5,051)	(3,701)
OCI before reclassifications	1,334	883	(1,350)
Amounts reclassified from AOCI	0	0	0
Total OCI, net of tax	1,334	883	(1,350)
Ending balance	(2,834)	(4,168)	(5,051)
Ownership Share of Equity Method Investees' OCI
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Beginning balance	0	0	0
OCI before reclassifications	0	0	0
Amounts reclassified from AOCI	0	0	0
Total OCI, net of tax	0	0	0
Ending balance	0	0	0
DB Plans
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Beginning balance	0	0	0
OCI before reclassifications	0	0	0
Amounts reclassified from AOCI	0	0	0
Total OCI, net of tax	0	0	0
Ending balance	0	0	0
Unrealized Gain (Loss) on Hedges
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Beginning balance	0	0	0
OCI before reclassifications	0	0	0
Amounts reclassified from AOCI	0	0	0
Total OCI, net of tax	0	0	0
Ending balance	$ 0	$ 0	$ 0