Supplemental Financial Statement Data Allowance for doubtful accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 30, 2017	Dec. 31, 2016	Jan. 02, 2016
Supplemental Financial Statement Data [Abstract]
Balance at beginning of year	$ 8	$ 8	$ 7
Additions charged to expense	14	9	4
Doubtful accounts charged to reserve	(12)	(9)	(3)
Balance at end of year	$ 10	$ 8	$ 8