Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended				12 Months Ended
	Oct. 31, 2019	Jan. 31, 2019	Oct. 31, 2018	Jan. 31, 2018	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2016
Cash flows from operating activities
Net income	$ 47.9	$ 13.0	$ 9.7	$ 27.8	$ 127.4	$ 97.8	$ 3.8
Loss (income) from discontinued operations, net of taxes	0.1	0.1	(0.8)	0.1	0.1	(1.8)	74.3
Income from continuing operations	48.1	13.0	8.9	28.0	127.5	95.9	78.1
Adjustments to reconcile income from continuing operations to net cash provided by operating activities of continuing operations
Depreciation and amortization					107.4	112.5	70.1
Proceeds from termination of interest rate swaps					0.0	25.9	0.0
Impairment loss (recovery)					0.0	26.5	(18.5)	$ 22.5
Deferred income taxes					9.7	(23.7)	(6.1)
Share-based compensation expense					17.5	17.0	13.3
Provision for bad debt					6.7	6.4	4.1
Discount accretion on insurance claims					0.8	0.8	0.2
(Gain) loss on sale of assets					(0.6)	0.5	(2.7)
Income from unconsolidated affiliates					(3.0)	(3.2)	(4.2)
Distributions from unconsolidated affiliates					5.4	1.9	5.7
Changes in operating assets and liabilities, net of effects of acquisitions
Trade accounts receivable and costs incurred in excess of amounts billed					(78.3)	16.0	(115.7)
Prepaid expenses and other current assets					(13.2)	2.4	(6.4)
Other noncurrent assets					4.5	11.3	(7.6)
Trade accounts payable and other accrued liabilities					85.8	(1.5)	74.4
Insurance claims					3.9	13.9	33.5
Income taxes payable					3.2	0.7	(22.5)
Other noncurrent liabilities					(14.4)	(3.7)	6.0
Total adjustments					135.3	203.7	23.6
Net cash provided by operating activities of continuing operations					262.8	299.7	101.7
Net cash (used in) provided by operating activities of discontinued operations					(0.1)	21.2	(96.1)
Net cash provided by operating activities					262.7	320.9	5.6
Cash flows from investing activities
Additions to property, plant and equipment					(59.6)	(50.9)	(57.2)
Proceeds from sale of assets					1.3	2.3	4.0
(Adjustments to) and proceeds from sale of business					0.0	(1.9)	35.5
Purchase of businesses, net of cash acquired					0.0	0.0	(853.6)
Proceeds from redemption of auction rate security					0.0	2.9	0.0
Investments in unconsolidated affiliates					0.0	(0.4)	(0.4)
Net cash used in investing activities					(58.3)	(48.1)	(871.8)
Cash flows from financing activities
Taxes withheld from issuance of share-based compensation awards, net					(1.3)	(1.0)	(0.7)
Repurchases of common stock					0.0	0.0	(7.9)
Dividends paid					(47.7)	(46.0)	(39.5)
Deferred financing costs paid					0.0	(0.1)	(18.7)
Borrowings from credit facility					1,755.9	1,184.2	1,880.1
Repayment of borrowings from credit facility					(1,896.5)	(1,426.4)	(957.2)
Changes in book cash overdrafts					(0.2)	(8.5)	15.8
Financing of energy savings performance contracts					8.1	5.4	6.8
Repayment of capital lease obligations					(3.1)	(3.3)	(0.9)
Payment of contingent consideration					0.0	0.0	(3.8)
Net cash (used in) provided by financing activities					(184.8)	(295.8)	874.0
Effect of exchange rate changes on cash and cash equivalents					(0.2)	(0.7)	1.5
Net increase (decrease) in cash and cash equivalents					19.4	(23.7)	9.3
Cash and cash equivalents at beginning of year		$ 39.1		$ 62.8	39.1	62.8	53.5
Cash and cash equivalents at end of year	$ 58.5		$ 39.1		58.5	39.1	62.8	$ 53.5
Supplemental cash flow information
Income tax payments (refunds), net					20.6	(1.0)	11.8
Interest paid on credit facility					39.9	49.6	8.1
Non-cash investing and financing activities
Stock issued in GCA acquisition, net of shares withheld for taxes					$ 0.0	$ 0.0	$ 421.3