Accounts receivable, net - Credit Quality Indicator and Age Analysis (Details) - USD ($) $ in Millions	Apr. 30, 2016	Jan. 30, 2016	May. 02, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross	$ (1,771.1)	$ (1,855.9)	$ (1,592.7)
Valuation allowance	$ (116.8)	$ (130.0)	$ (103.3)
Gross	100.00%	100.00%	100.00%
Valuation allowance	6.60%	7.00%	6.50%
Financing Receivables, 1 to 29 Days Past Due | Performing Financing Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross	$ (1,427.5)	$ (1,473.0)	$ (1,290.9)
Valuation allowance	$ (43.4)	$ (45.4)	$ (39.3)
Gross	80.60%	79.40%	81.00%
Valuation allowance	3.00%	3.10%	3.00%
Financing Receivables, 30 to 59 Days Past Due | Performing Financing Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross	$ (240.9)	$ (259.6)	$ (211.6)
Valuation allowance	$ (7.9)	$ (8.3)	$ (6.8)
Gross	13.60%	14.00%	13.30%
Valuation allowance	3.30%	3.20%	3.20%
Financing Receivables, 60 to 89 Days Past Due | Performing Financing Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross	$ (39.2)	$ (49.2)	$ (34.8)
Valuation allowance	$ (2.0)	$ (2.2)	$ (1.8)
Gross	2.20%	2.60%	2.20%
Valuation allowance	5.10%	4.50%	5.20%
Financing Receivables, Equal to Greater than 90 Days Past Due | Nonperforming Financing Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross	$ (63.5)	$ (74.1)	$ (55.4)
Valuation allowance	$ (63.5)	$ (74.1)	$ (55.4)
Gross	3.60%	4.00%	3.50%
Valuation allowance	100.00%	100.00%	100.00%