New accounting pronouncements - Effects of the Adoption of ASC 842 (Details) - USD ($) $ in Millions	May 04, 2019	Feb. 03, 2019	Feb. 02, 2019	May 05, 2018
Current assets:
Other current assets	$ 205.5	$ 235.2	$ 244.0	$ 236.8
Non-current assets:
Operating lease right-of-use assets	1,822.8	1,927.2
Current liabilities:
Accrued expenses and other current liabilities	420.2	393.8	502.8	463.7
Operating lease liabilities	358.9	376.5
Non-current liabilities:
Operating lease liabilities	1,589.4	1,676.9
Other liabilities	$ 126.0	198.1	$ 224.1	$ 236.5
Accounting Standards Update 2016-02
Current assets:
Other current assets		(8.8)
Non-current assets:
Operating lease right-of-use assets		1,927.2
Current liabilities:
Accrued expenses and other current liabilities		(109.0)
Operating lease liabilities		376.5
Non-current liabilities:
Operating lease liabilities		1,676.9
Other liabilities		$ (26.0)