Segment Information - Financial Information by Reportable Segment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2019	Apr. 30, 2018
Revenues
Revenues	$ 1,594.7	$ 1,580.8	$ 3,202.6	$ 3,169.2
Operating profit (loss)
Operating profit (loss)	54.5	45.3	84.8	64.8
Income from unconsolidated affiliates	0.8	1.0	1.7	1.6
Interest expense	(12.8)	(13.8)	(26.3)	(28.1)
Income from continuing operations before income taxes	42.5	32.5	60.2	38.2
Operating Segments
Revenues
Revenues	1,627.3		3,269.6
Intersegment Eliminations
Revenues
Revenues	(32.6)	(36.5)	(67.0)	(75.4)
Corporate
Operating profit (loss)
Operating profit (loss)	(38.9)	(37.1)	(83.6)	(84.5)
Segment Reconciling Items
Operating profit (loss)
Income from unconsolidated affiliates	(0.8)	(1.0)	(1.7)	(1.6)
Adjustment for tax deductions for energy efficient government buildings, included in Technical Solutions	0.0	(2.0)	0.0	(2.3)
Business & Industry | Operating Segments
Revenues
Revenues	753.4	755.1	1,527.9	1,511.3
Operating profit (loss)
Operating profit (loss)	47.7	43.5	84.2	72.0
Aviation | Operating Segments
Revenues
Revenues	250.0	249.2	502.4	509.2
Operating profit (loss)
Operating profit (loss)	4.8	5.1	8.7	10.9
Technology & Manufacturing | Operating Segments
Revenues
Revenues	224.3	227.8	460.4	460.0
Operating profit (loss)
Operating profit (loss)	19.2	16.0	37.4	32.9
Education | Operating Segments
Revenues
Revenues	205.6	206.9	410.3	413.8
Operating profit (loss)
Operating profit (loss)	10.4	10.6	20.6	19.8
Technical Solutions | Operating Segments
Revenues
Revenues	127.6	108.5	235.5	212.5
Operating profit (loss)
Operating profit (loss)	9.5	7.5	15.5	13.0
Healthcare | Operating Segments
Revenues
Revenues	66.3	69.9	133.0	137.6
Operating profit (loss)
Operating profit (loss)	2.6	2.7	3.8	5.4
Government Services | Operating Segments
Operating profit (loss)
Operating profit (loss)	$ 0.0	$ 0.0	$ (0.1)	$ (0.8)