Debt (Details) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
	Oct. 28, 2017 USD ($) CreditFacility	Oct. 28, 2017 USD ($) CreditFacility	Jan. 28, 2017 USD ($) CreditFacility
Line of Credit Facility [Line Items]
Number of unsecured credit facilities | CreditFacility	2	2	2
Available borrowings under credit facilities	$ 80.0	$ 80.0	$ 80.0
Days borrowings incurred against facilities	0 days	7 days	19 days
Average borrowings outstanding	$ 0.0	$ 4.2	$ 6.6
Maximum borrowings outstanding	$ 0.0	$ 4.9	$ 11.8
Average interest rate on outstanding borrowings	0.00%	2.80%	2.50%
August 2016 Facility [Member]
Line of Credit Facility [Line Items]
Expiration date of renewed facility	Nov. 30, 2017
Maximum borrowing capacity under renewed facility	$ 30.0	$ 30.0
Line of Credit Facility, Interest Rate Description	one month LIBOR plus 2.0%
Description of variable interest rate basis	one month LIBOR
Basis spread on variable interest rate (in hundredths)	2.00%
Debt outstanding at period end	$ 0.0	0.0
November 2016 Facility [Member]
Line of Credit Facility [Line Items]
Expiration date of renewed facility	Nov. 18, 2017
Maximum borrowing capacity under renewed facility	$ 50.0	50.0
Line of Credit Facility, Interest Rate Description	a rate agreed upon between the lender and borrower at the time loan is made
Debt outstanding at period end	$ 0.0	$ 0.0