Accounts receivable, net - Credit Quality Indicator and Age Analysis (Details) - USD ($) $ in Millions	Jul. 30, 2016	Jan. 30, 2016	Aug. 01, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross	$ (1,745.0)	$ (1,855.9)	$ (1,599.1)
Valuation allowance	$ (129.4)	$ (130.0)	$ (116.0)
Gross	100.00%	100.00%	100.00%
Valuation allowance	7.40%	7.00%	7.30%
Financing Receivables, 1 to 29 Days Past Due | Performing Financing Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross	$ (1,350.7)	$ (1,473.0)	$ (1,252.4)
Valuation allowance	$ (41.3)	$ (45.4)	$ (38.1)
Gross	77.40%	79.40%	78.30%
Valuation allowance	3.10%	3.10%	3.00%
Financing Receivables, 30 to 59 Days Past Due | Performing Financing Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross	$ (264.1)	$ (259.6)	$ (232.3)
Valuation allowance	$ (8.6)	$ (8.3)	$ (7.5)
Gross	15.10%	14.00%	14.50%
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	$ (53.2)	$ (49.2)	$ (46.1)
Valuation allowance	$ (2.5)	$ (2.2)	$ (2.1)
Gross	3.10%	2.60%	2.90%
Valuation allowance	4.70%	4.50%	4.60%
Financing Receivables, Equal to Greater than 90 Days Past Due | Nonperforming Financing Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross	$ (77.0)	$ (74.1)	$ (68.3)
Valuation allowance	$ (77.0)	$ (74.1)	$ (68.3)
Gross	4.40%	4.00%	4.30%
Valuation allowance	100.00%	100.00%	100.00%