Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jan. 31, 2021	Oct. 31, 2020	Jan. 31, 2020	Jan. 31, 2021	Jan. 31, 2020	Jul. 31, 2020
Accumulated Other Comprehensive Income (Loss), Net of Tax
Beginning Balance	$ 1,052.6	$ 992.9	$ 917.0	$ 992.9	$ 892.7
Other comprehensive income (loss) before reclassifications and tax	39.8		2.4	39.1	10.6
Tax (expense) benefit	0.3		0.5	(0.7)	0.7
Other comprehensive income (loss) before reclassifications, net of tax	40.1		2.9	38.4	11.3
Reclassifications, before tax	(0.5)		1.7	3.1	4.3
Tax (expense) benefit	0.2		(0.4)	(0.5)	(1.0)
Reclassifications, net of tax	(0.3)		1.3	2.6	3.3
Other comprehensive income (loss), net of tax	39.8		4.2	41.0	14.6
Ending Balance	1,074.4	1,052.6	940.4	1,074.4	940.4
Accumulated other comprehensive loss	(143.0)			(143.0)		$ (184.0)
Reclassification, Other
Accumulated Other Comprehensive Income (Loss), Net of Tax
Curtailment charge		0.8
Accumulated other comprehensive loss		4.0
Total
Accumulated Other Comprehensive Income (Loss), Net of Tax
Beginning Balance	(182.8)	(184.0)	(182.5)	(184.0)	(192.9)
Other comprehensive income (loss), net of tax	39.8		4.2	41.0	14.6
Ending Balance	(143.0)	(182.8)	(178.3)	(143.0)	(178.3)
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss), Net of Tax
Beginning Balance	(79.0)	(74.0)	(84.6)	(74.0)	(92.7)
Other comprehensive income (loss) before reclassifications and tax	41.5		2.4	36.5	10.5
Tax (expense) benefit	0.0		0.0	0.0	0.0
Other comprehensive income (loss) before reclassifications, net of tax	41.5		2.4	36.5	10.5
Reclassifications, before tax	0.0		0.0	0.0	0.0
Tax (expense) benefit	0.0		0.0	0.0	0.0
Reclassifications, net of tax	0.0		0.0	0.0	0.0
Other comprehensive income (loss), net of tax	41.5		2.4	36.5	10.5
Ending Balance	(37.5)	(79.0)	(82.2)	(37.5)	(82.2)
Pension Benefits
Accumulated Other Comprehensive Income (Loss), Net of Tax
Beginning Balance	(103.9)	(110.0)	(98.2)	(110.0)	(99.0)
Other comprehensive income (loss) before reclassifications and tax	0.0		0.0	4.0	0.0
Tax (expense) benefit	0.0		0.0	(1.0)	0.0
Other comprehensive income (loss) before reclassifications, net of tax	0.0		0.0	3.0	0.0
Reclassifications, before tax	0.2		1.6	3.8	2.3
Tax (expense) benefit	(0.2)		(0.4)	(0.7)	(0.3)
Reclassifications, net of tax	0.0		1.2	3.1	2.0
Other comprehensive income (loss), net of tax	0.0		1.2	6.1	2.0
Ending Balance	(103.9)	(103.9)	(97.0)	(103.9)	(97.0)
Derivative Financial Instruments
Accumulated Other Comprehensive Income (Loss), Net of Tax
Beginning Balance	0.1	0.0	0.3	0.0	(1.2)
Other comprehensive income (loss) before reclassifications and tax	(1.7)		0.0	(1.4)	0.1
Tax (expense) benefit	0.3		0.5	0.3	0.7
Other comprehensive income (loss) before reclassifications, net of tax	(1.4)		0.5	(1.1)	0.8
Reclassifications, before tax	(0.7)		0.1	(0.7)	2.0
Tax (expense) benefit	0.4		0.0	0.2	(0.7)
Reclassifications, net of tax	(0.3)		0.1	(0.5)	1.3
Other comprehensive income (loss), net of tax	(1.7)		0.6	(1.6)	2.1
Ending Balance	$ (1.6)	$ 0.1	$ 0.9	$ (1.6)	$ 0.9