Segment Information - Financial Information by Reportable Segment (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2020	Apr. 30, 2019
Revenues
Revenues	$ 1,496.0	$ 1,594.7	$ 3,109.0	$ 3,202.6
Operating (loss) profit
Operating (loss) profit	(116.7)	54.5	(70.8)	84.8
Income from unconsolidated affiliates	0.9	0.8	1.8	1.7
Interest expense	(10.5)	(12.8)	(20.7)	(26.3)
(Loss) income from continuing operations before income taxes	(126.2)	42.5	(89.7)	60.2
Impairment loss	172.8	0.0	172.8	0.0
Goodwill, impairment loss	163.8		163.8
Operating Segments
Revenues
Revenues	1,526.4	1,627.3	3,170.0	3,269.6
Elimination of inter-segment revenues
Revenues
Revenues	(30.4)	(32.6)	(61.0)	(67.0)
Corporate
Operating (loss) profit
Operating (loss) profit	(39.5)	(38.9)	(72.8)	(83.6)
Segment Reconciling Items
Operating (loss) profit
Income from unconsolidated affiliates	(0.9)	(0.8)	(1.8)	(1.7)
Adjustment for tax deductions for energy efficient government buildings, included in Technical Solutions	(0.4)	0.0	(0.4)	0.0
Business & Industry \| Operating Segments
Revenues
Revenues	785.6	807.7	1,606.5	1,636.6
Operating (loss) profit
Operating (loss) profit	59.2	49.2	97.4	86.0
Technology & Manufacturing \| Operating Segments
Revenues
Revenues	233.7	224.3	467.6	460.4
Operating (loss) profit
Operating (loss) profit	19.7	19.2	36.3	37.4
Aviation
Operating (loss) profit
Impairment loss	61.1		61.1
Goodwill, impairment loss	55.5		55.5
Aviation \| Operating Segments
Revenues
Revenues	184.7	250.0	423.5	502.4
Operating (loss) profit
Operating (loss) profit	(60.5)	4.8	(54.9)	8.7
Education
Operating (loss) profit
Goodwill, impairment loss	99.3		99.3
Education \| Operating Segments
Revenues
Revenues	200.1	209.3	408.0	418.2
Operating (loss) profit
Operating (loss) profit	(85.8)	10.5	(74.6)	20.8
Technical Solutions
Operating (loss) profit
Impairment loss	12.4		12.4
Goodwill, impairment loss	9.0		9.0
Technical Solutions \| Operating Segments
Revenues
Revenues	122.3	135.9	264.3	252.0
Operating (loss) profit
Operating (loss) profit	(8.4)	10.6	(0.1)	17.3
Government Services \| Operating Segments
Operating (loss) profit
Operating (loss) profit	$ 0.0	$ 0.0	$ 0.0	$ (0.1)

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