Accounts receivable, net - Portfolio of Accounts Receivable (Details) - USD ($) $ in Millions	Jul. 29, 2017	Jan. 28, 2017	Jul. 30, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, net	$ 664.5	$ 1,858.0	$ 1,650.6
Accounts receivable, held for sale	1,055.6	0.0	0.0
Consumer Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, net	622.6		1,615.6
Other Accounts Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, net	7.9	11.3	10.0
Sterling Jewelers | Consumer Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, net	622.6	1,813.3	1,615.6
Zale Jewelry | Consumer Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, net	$ 34.0	$ 33.4	$ 25.0