SEGMENT AND GEOGRAPHIC INFORMATION - Schedule of Financial Information by Reportable Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Oct. 31, 2025	Oct. 31, 2024	Oct. 31, 2023
Revenues
Revenues	$ 8,745.9	$ 8,359.4	$ 8,096.4
Significant segment expenses
Operating profit	311.7	212.0	409.5
Income from unconsolidated affiliates	4.6	6.5	3.9
Interest expense	(96.4)	(85.0)	(82.3)
Income before income taxes	219.9	133.6	331.1
Other significant segment items
Change in fair value of contingent consideration	(1.6)	95.7	(45.6)
Employee retention credit	1.2		24.0
Depreciation and amortization	105.6	106.6	120.7
B&I
Revenues
Revenues	4,126.0	4,059.1
M&D
Revenues
Revenues	1,618.6	1,554.3
Aviation
Revenues
Revenues	1,118.7	1,032.6
Education
Revenues
Revenues	922.0	904.0
Technical Solutions
Revenues
Revenues	960.6	809.3
Operating Segments
Revenues
Revenues	8,745.9	8,359.4	8,096.4
Significant segment expenses
Direct labor	4,917.9	4,693.7	4,638.2
Indirect costs	278.0	273.4	250.9
General and administrative	261.5	262.9	239.6
Selling	101.2	88.5	91.4
Other segment expense	2,499.5	2,383.6	2,235.8
Operating profit	687.6	657.2	640.3
Operating Segments | B&I
Revenues
Revenues	4,126.0	4,059.1	4,089.4
Significant segment expenses
Direct labor	2,290.1	2,239.9	2,265.6
Indirect costs	119.8	134.5	135.0
General and administrative	88.3	92.7	91.0
Selling	33.2	28.8	32.5
Other segment expense	1,277.6	1,256.2	1,249.6
Operating profit	316.9	307.0	315.6
Other significant segment items
Materials and supplies	109.2	119.9	116.9
Salaries and wages (other than direct)	126.7	131.3	133.6
Consulting and professional services	11.8	12.5	14.4
Travel and entertainment (other than direct)	8.6	9.6	8.6
Legal	7.2	9.6	3.7
Depreciation and amortization	35.0	37.3	44.9
Operating Segments | M&D
Revenues
Revenues	1,618.6	1,554.3	1,526.7
Significant segment expenses
Direct labor	1,058.6	996.5	995.4
Indirect costs	31.0	20.8	19.0
General and administrative	45.2	49.5	47.3
Selling	12.9	7.8	5.7
Other segment expense	319.4	313.5	297.6
Operating profit	151.4	166.3	161.7
Other significant segment items
Materials and supplies	58.5	73.5	68.2
Salaries and wages (other than direct)	32.1	25.7	21.4
Consulting and professional services	5.3	5.6	4.7
Travel and entertainment (other than direct)	3.4	2.1	1.7
Legal	1.7	1.5	2.4
Depreciation and amortization	11.7	12.2	13.1
Operating Segments | Aviation
Revenues
Revenues	1,118.7	1,032.6	925.7
Significant segment expenses
Direct labor	657.2	596.7	536.2
Indirect costs	12.9	16.7	15.8
General and administrative	41.4	41.8	38.9
Selling	1.6	1.5	0.7
Other segment expense	340.5	316.8	274.1
Operating profit	65.2	59.1	60.0
Other significant segment items
Materials and supplies	22.3	21.8	24.8
Salaries and wages (other than direct)	16.2	18.5	16.9
Consulting and professional services	46.0	45.0	29.1
Travel and entertainment (other than direct)	2.1	1.8	1.4
Legal	2.5	2.1	0.2
Depreciation and amortization	14.1	12.6	9.6
Operating Segments | Education
Revenues
Revenues	922.0	904.0	880.5
Significant segment expenses
Direct labor	605.7	598.4	590.5
Indirect costs	23.4	25.0	19.8
General and administrative	9.5	11.5	11.0
Selling	1.4	1.3	2.9
Other segment expense	214.3	212.5	206.5
Operating profit	67.7	55.3	49.7
Other significant segment items
Materials and supplies	47.5	49.1	48.3
Salaries and wages (other than direct)	16.3	19.0	18.0
Consulting and professional services	4.0	3.0	3.3
Travel and entertainment (other than direct)	1.5	1.2	1.1
Legal	1.0	0.8	0.5
Depreciation and amortization	21.3	21.8	22.5
Operating Segments | Technical Solutions
Revenues
Revenues	960.6	809.3	674.2
Significant segment expenses
Direct labor	306.2	262.2	250.6
Indirect costs	91.0	76.5	61.3
General and administrative	77.1	67.5	51.4
Selling	52.1	49.1	49.7
Other segment expense	347.9	284.6	208.0
Operating profit	86.5	69.4	53.2
Other significant segment items
Materials and supplies	280.8	242.0	154.8
Salaries and wages (other than direct)	130.4	107.9	94.1
Consulting and professional services	9.2	7.4	4.1
Travel and entertainment (other than direct)	6.5	5.3	4.3
Legal	1.2	0.9	0.6
Depreciation and amortization	10.4	7.7	17.5
Corporate
Significant segment expenses
Operating profit	(370.5)	(433.1)	(226.7)
Other significant segment items
Depreciation and amortization	13.1	15.0	13.1
Corporate | RavenVolt
Other significant segment items
Change in fair value of contingent consideration		(95.7)	(45.6)
Employee retention credit			24.0
Segment Reporting, Reconciling Item, Excluding Corporate Nonsegment
Significant segment expenses
Income from unconsolidated affiliates	(4.6)	(6.5)	(3.9)
Adjustment for tax deductions for energy efficient government buildings, included in Technical Solutions	$ (0.8)	$ (5.5)	$ (0.3)