Accounting Policies Summary of Significant Accounting Policies (Details) - Consumer credit receivable - USD ($) $ in Millions	Oct. 31, 2015	Jan. 31, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Consumer credit receivable, net	$ 944	$ 1,200
Consumer credit receivable, reserve for doubtful accounts	$ 71	$ 114