Income Taxes Reconciliation of Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits at beginning of period	$ 7.2	$ 14.0	$ 12.1
Gross increases - tax positions in prior period	3.2	0.9	1.0
Gross decreases - tax positions in prior period	(0.9)	(5.0)	(0.4)
Gross increases - tax positions in current period	0.6	0.3	1.4
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	0.0	(3.0)	0.0
Lapse of Statute of Limitations	0.0	0.0	(0.1)
Unrecognized Tax Benefits at end of period	$ 10.1	$ 7.2	$ 14.0