Long-term debt (Tables)

12 Months Ended

Jan. 31, 2016

Debt Disclosure [Abstract]

Schedule of Long-term Debt Instruments

	January 31, 2016			January 25, 2015
	(In millions)
Amount of the equity component	$	39		$	126
1.00% Convertible Senior Notes Due 2018	$	1,500		$	1,500
Unamortized debt discount (1)	(87		)	(116		)
Net carrying amount	$	1,413		$	1,384

(1) As of January 31, 2016, the remaining period over which the unamortized debt discount will be amortized is 2.8 years.

The following table presents the interest expense for the contractual interest and the accretion of debt discount:

	Year Ended
	January 31, 2016		January 25, 2015		January 26, 2014
	(In millions)
Contractual coupon interest expense	$	15	$	15	$	2
Amortization of debt discount	29		28		5
Total interest expense related to Notes	$	44	$	43	$	7