XML 30 R17.htm IDEA: XBRL DOCUMENT v3.7.0.1
Fair Value Measurements (Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis) (Details) - USD ($)
$ in Billions
Apr. 30, 2017
Jan. 29, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Carrying value of senior notes $ 22.0 $ 22.0
Senior Notes [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair value of senior notes $ 24.0 $ 23.6