Goodwill and Intangible Assets (Major Asset Classes) (Details) - USD ($) $ in Millions	3 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Jan. 31, 2020
Goodwill and Intangible Assets Disclosure [Line Items]
Original Cost	$ 11.8		$ 51.0
Accumulated Amortization	6.3		5.2
Impairment charge	39.2
Net Book Value	5.5		45.8
Amortization expense of intangible assets	1.0	$ 0.8
Property and equipment	158.1		306.8
Long-lived asset impairment charge	180.4
Asset impairment charge	208.7
Long-lived asset impairment charge, property and equipment	141.2
Goodwill [Roll Forward]
Goodwill, Beginning Balance	28.3
Goodwill impairment	(28.3)
Goodwill, Ending Balance	$ 0.0
Customer contracts and relationships
Goodwill and Intangible Assets Disclosure [Line Items]
Useful Life (years)	20 years
Original Cost	$ 8.3		43.0
Accumulated Amortization	2.9		2.4
Net Book Value	5.4		40.6
Covenants not to compete
Goodwill and Intangible Assets Disclosure [Line Items]
Original Cost	2.5		4.7
Accumulated Amortization	2.4		1.9
Net Book Value	$ 0.1		2.8
Covenants not to compete | Minimum
Goodwill and Intangible Assets Disclosure [Line Items]
Useful Life (years)	1 year 6 months
Covenants not to compete | Maximum
Goodwill and Intangible Assets Disclosure [Line Items]
Useful Life (years)	3 years
Developed Technologies
Goodwill and Intangible Assets Disclosure [Line Items]
Useful Life (years)	15 years
Original Cost	$ 1.0		3.3
Accumulated Amortization	1.0		0.9
Net Book Value			$ 2.4
Southwest
Goodwill and Intangible Assets Disclosure [Line Items]
Asset impairment charge	91.3
Impairment charge	$ 91.3
Rocky Mountains
Goodwill and Intangible Assets Disclosure [Line Items]
Percentage of undiscounted cash flows exceeding carrying value of assets	20.50%
Asset impairment charge	$ 28.3
Goodwill [Roll Forward]
Goodwill, Beginning Balance	28.3
Goodwill impairment	(28.3)
Goodwill, Ending Balance	0.0
Northeast/Mid-Con
Goodwill and Intangible Assets Disclosure [Line Items]
Asset impairment charge	89.1
Impairment charge	$ 89.1