Goodwill and Long-Lived Assets, Net (Major Asset Classes) (Details) - USD ($) $ in Millions	3 Months Ended
	Apr. 30, 2018	Jan. 31, 2018
Goodwill and Intangible Assets Disclosure [Line Items]
Original Cost	$ 436.5	$ 438.6
Accumulated Amortization	134.2	130.0
Net Book Value	302.3	308.6
Trade names
Goodwill and Intangible Assets Disclosure [Line Items]
Original Cost	18.9	19.5
Net Book Value	18.9	19.5
Customer contracts and relationships
Goodwill and Intangible Assets Disclosure [Line Items]
Original Cost	412.1	413.6
Accumulated Amortization	132.9	128.8
Net Book Value	$ 279.2	284.8
Customer contracts and relationships | Minimum
Goodwill and Intangible Assets Disclosure [Line Items]
Useful Life (years)	10 years
Customer contracts and relationships | Maximum
Goodwill and Intangible Assets Disclosure [Line Items]
Useful Life (years)	30 years
Covenants not to compete
Goodwill and Intangible Assets Disclosure [Line Items]
Useful Life (years)	5 years
Original Cost	$ 2.2	2.2
Accumulated Amortization	0.8	0.7
Net Book Value	$ 1.4	1.5
Developed Technologies
Goodwill and Intangible Assets Disclosure [Line Items]
Useful Life (years)	15 years
Original Cost	$ 3.3	3.3
Accumulated Amortization	0.5	0.5
Net Book Value	$ 2.8	$ 2.8