Organization and summary of significant accoutning policies - Cash and Equivalents (Details) - USD ($) $ in Millions	Feb. 02, 2019	Feb. 03, 2018	Jan. 28, 2017	Jan. 30, 2016
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 195.4	$ 225.1	$ 98.7	$ 137.7
Cash and cash equivalents held in money markets and other accounts
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	164.5	182.6
Cash equivalents from third-party credit card issuers
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	29.1	40.5
Cash on hand
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 1.8	$ 2.0