Other Comprehensive Income (Loss) - Changes in AOCI Balances by Component (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Changes in AOCI balances by component (after-tax)
Balance, beginning of year	$ 1,907	$ 1,645	$ 1,996	$ 1,567
Total OCI, net of tax	17	(17)	63	12
Balance, end of year	1,970	1,694	1,970	1,694
Attributable to Fluor:
Changes in AOCI balances by component (after-tax)
Balance, beginning of year	(319)	(337)	(365)	(366)
OCI before reclassifications	16	(28)	61	4
Amounts reclassified from AOCI	1	10	2	7
Total OCI, net of tax	17	(18)	63	11
Balance, end of year	(302)	(355)	(302)	(355)
Foreign Currency Translation
Changes in AOCI balances by component (after-tax)
Balance, beginning of year	(282)	(271)	(328)	(300)
OCI before reclassifications	19	(34)	65	(5)
Amounts reclassified from AOCI	0	0	0	0
Total OCI, net of tax	19	(34)	65	(5)
Balance, end of year	(263)	(305)	(263)	(305)
Ownership Share of Equity Method Investees’ OCI
Changes in AOCI balances by component (after-tax)
Balance, beginning of year	(26)	(55)	(25)	(56)
OCI before reclassifications	(3)	10	(4)	10
Amounts reclassified from AOCI	0	7	0	8
Total OCI, net of tax	(3)	17	(4)	18
Balance, end of year	(29)	(38)	(29)	(38)
Other
Changes in AOCI balances by component (after-tax)
Balance, beginning of year	(11)	(11)	(12)	(10)
OCI before reclassifications	0	(4)	0	(1)
Amounts reclassified from AOCI	1	3	2	(1)
Total OCI, net of tax	1	(1)	2	(2)
Balance, end of year	(10)	(12)	(10)	(12)
Attributable to NCI:
Changes in AOCI balances by component (after-tax)
Balance, beginning of year	(2)	(3)	(2)	(3)
OCI before reclassifications	0	1	0	1
Amounts reclassified from AOCI	0	0	0	0
Total OCI, net of tax	0	1	0	1
Balance, end of year	(2)	(2)	(2)	(2)
Foreign Currency Translation
Changes in AOCI balances by component (after-tax)
Balance, beginning of year	(2)	(3)	(2)	(3)
OCI before reclassifications	0	1	0	1
Amounts reclassified from AOCI	0	0	0	0
Total OCI, net of tax	0	1	0	1
Balance, end of year	(2)	(2)	(2)	(2)
Ownership Share of Equity Method Investees’ OCI
Changes in AOCI balances by component (after-tax)
Balance, beginning of year	0	0	0	0
OCI before reclassifications	0	0	0	0
Amounts reclassified from AOCI	0	0	0	0
Total OCI, net of tax	0	0	0	0
Balance, end of year	0	0	0	0
Other
Changes in AOCI balances by component (after-tax)
Balance, beginning of year	0	0	0	0
OCI before reclassifications	0	0	0	0
Amounts reclassified from AOCI	0	0	0	0
Total OCI, net of tax	0	0	0	0
Balance, end of year	$ 0	$ 0	$ 0	$ 0