Segment Information - Financial Information by Reportable Segment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2019	Jul. 31, 2018
Revenues
Revenues	$ 1,647.9	$ 1,624.3	$ 4,850.6	$ 4,793.5
Operating profit (loss)
Operating profit (loss)	57.3	48.1	142.1	112.9
Income from unconsolidated affiliates	0.7	1.0	2.4	2.5
Interest expense	(12.9)	(12.9)	(39.2)	(41.0)
Income from continuing operations before income taxes	45.0	36.1	105.3	74.4
Operating Segments
Revenues
Revenues	1,679.3		4,948.9
Elimination of inter-segment revenues
Revenues
Revenues	(31.3)	(36.0)	(98.3)	(111.4)
Corporate
Operating profit (loss)
Operating profit (loss)	(43.5)	(42.7)	(127.1)	(127.3)
Segment Reconciling Items
Operating profit (loss)
Adjustment for tax deductions for energy efficient government buildings, included in Technical Solutions	0.1	(0.3)	0.1	(2.6)
Income from unconsolidated affiliates	(0.7)	(0.9)	(2.4)	(2.5)
Business & Industry | Operating Segments
Revenues
Revenues	807.9	822.6	2,444.5	2,446.0
Operating profit (loss)
Operating profit (loss)	45.3	40.1	131.2	114.8
Aviation | Operating Segments
Revenues
Revenues	263.3	260.5	765.8	769.7
Operating profit (loss)
Operating profit (loss)	8.6	9.7	17.2	20.6
Technology & Manufacturing | Operating Segments
Revenues
Revenues	226.9	231.0	687.3	691.0
Operating profit (loss)
Operating profit (loss)	17.0	16.9	54.4	49.8
Education | Operating Segments
Revenues
Revenues	215.4	215.9	633.6	637.8
Operating profit (loss)
Operating profit (loss)	12.6	12.1	33.4	32.1
Technical Solutions | Operating Segments
Revenues
Revenues	165.7	130.3	417.7	360.3
Operating profit (loss)
Operating profit (loss)	17.9	13.1	35.3	28.8
Government Services | Operating Segments
Operating profit (loss)
Operating profit (loss)	$ 0.0	$ 0.0	$ (0.1)	$ (0.8)