Segment Information - Financial Information by Reportable Segment (Details) - USD ($)	3 Months Ended		9 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
Revenues
Revenues	$ 1,394,100,000	$ 1,647,900,000	$ 4,503,000,000.0	$ 4,850,600,000
Operating profit (loss)
Operating profit (loss)	93,600,000	57,300,000	22,800,000	142,100,000
Income from unconsolidated affiliates	200,000	700,000	2,000,000.0	2,400,000
Interest expense	(13,800,000)	(12,900,000)	(34,500,000)	(39,200,000)
Income (loss) from continuing operations before income taxes	80,000,000.0	45,000,000.0	(9,700,000)	105,300,000
Impairment loss	0	0	172,800,000	0
Goodwill, impairment loss	0		163,800,000
Operating Segments
Revenues
Revenues	1,424,200,000	1,679,300,000	4,594,100,000	4,948,900,000
Elimination of inter-segment revenues
Revenues
Revenues	(30,100,000)	(31,300,000)	(91,100,000)	(98,300,000)
Corporate
Operating profit (loss)
Operating profit (loss)	(24,800,000)	(43,500,000)	(97,700,000)	(127,100,000)
Segment Reconciling Items
Operating profit (loss)
Income from unconsolidated affiliates	(200,000)	(700,000)	(2,000,000.0)	(2,400,000)
Adjustment for tax deductions for energy efficient government buildings, included in Technical Solutions	(800,000)	100,000	(1,200,000)	100,000
Business & Industry | Operating Segments
Revenues
Revenues	756,900,000	807,900,000	2,363,400,000	2,444,500,000
Operating profit (loss)
Operating profit (loss)	71,600,000	45,300,000	169,100,000	131,200,000
Technology & Manufacturing | Operating Segments
Revenues
Revenues	243,200,000	226,900,000	710,800,000	687,300,000
Operating profit (loss)
Operating profit (loss)	24,500,000	17,000,000.0	60,900,000	54,400,000
Education
Operating profit (loss)
Goodwill, impairment loss			99,300,000
Education | Operating Segments
Revenues
Revenues	188,600,000	215,400,000	596,600,000	633,600,000
Operating profit (loss)
Operating profit (loss)	18,300,000	12,600,000	(56,300,000)	33,400,000
Aviation
Operating profit (loss)
Impairment loss			61,100,000
Goodwill, impairment loss			55,500,000
Aviation | Operating Segments
Revenues
Revenues	116,400,000	263,300,000	539,900,000	765,800,000
Operating profit (loss)
Operating profit (loss)	(8,200,000)	8,600,000	(63,000,000.0)	17,200,000
Technical Solutions
Operating profit (loss)
Impairment loss			12,400,000
Goodwill, impairment loss			9,000,000.0
Technical Solutions | Operating Segments
Revenues
Revenues	119,200,000	165,700,000	383,500,000	417,700,000
Operating profit (loss)
Operating profit (loss)	13,200,000	17,900,000	13,100,000	35,300,000
Government Services | Operating Segments
Operating profit (loss)
Operating profit (loss)	$ 0	$ 0	$ 0	$ (100,000)