Investments - Summary of Available-for-sale Securities (Details) - USD ($) $ in Millions	Feb. 01, 2020	Feb. 02, 2019
Debt Securities, Available-for-sale [Line Items]
Total investment in debt securities	$ 20.1	$ 15.7
Unrealized Gain (Loss)	0.3	(0.9)
Fair Value	20.4	14.8
US Treasury securities
Debt Securities, Available-for-sale [Line Items]
Total investment in debt securities	7.2	5.1
Unrealized Gain (Loss)	0.0	(0.4)
Fair Value	7.2	4.7
US government agency securities
Debt Securities, Available-for-sale [Line Items]
Total investment in debt securities	4.6	2.6
Unrealized Gain (Loss)	0.1	(0.1)
Fair Value	4.7	2.5
Corporate bonds and notes
Debt Securities, Available-for-sale [Line Items]
Total investment in debt securities	8.3	5.3
Unrealized Gain (Loss)	0.2	(0.1)
Fair Value	8.5	5.2
Corporate equity securities
Debt Securities, Available-for-sale [Line Items]
Total investment in debt securities	0.0	2.7
Unrealized Gain (Loss)	0.0	(0.3)
Fair Value	$ 0.0	$ 2.4