Income Taxes (Income Tax Expense) (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2015	Jan. 31, 2017	Jan. 31, 2016	Dec. 31, 2014
Current:
Federal	$ 3.5		$ 0.7	$ 75.4
State	0.4	$ 0.3	(1.5)	8.5
Foreign	0.8	(1.3)	3.8	29.0
Total current income tax expense	4.7	(1.0)	3.0	112.9
Deferred:
Federal		14.4	(213.3)	42.8
State		1.3	(17.4)	3.5
Foreign	(0.4)	(9.4)	(0.6)	(3.5)
Total deferred income tax expense (benefit)	(0.4)	6.3	(231.3)	42.8
Total income tax (benefit) expense	$ 4.3	$ 5.3	$ (228.3)	$ 155.7