Income Taxes - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 31, 2017	Oct. 31, 2016	Oct. 31, 2017	Oct. 31, 2016
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation, Percent	33.40%	34.60%	32.90%	33.00%
Unrecognized Tax Benefits, Period Increase (Decrease)				$ 6.8
Return to Provision Adjustment [Member]
Discrete Tax Items [Line Items]
Effective Income Tax Rate Reconciliation, Other Adjustments, Percent	(2.50%)		(0.80%)
Change in Federal Tax Legislation [Member]
Discrete Tax Items [Line Items]
Effective Income Tax Rate Reconciliation, Other Adjustments, Percent	0.80%		0.30%
Tax Settlement [Member]
Discrete Tax Items [Line Items]
Tax Adjustments, Settlements, and Unusual Provisions				$ (6.6)
Effective Income Tax Rate Reconciliation, Other Adjustments, Percent				(1.50%)
ASU 2016-09 [Member]
Discrete Tax Items [Line Items]
Effective Income Tax Rate Reconciliation, Share-based Compensation Excess Tax Benefit Amount	$ 0.4		$ 3.5
Effective Income Tax Rate Reconciliation, Deduction, Other, Percent			(0.80%)