Accounts Receivable and Finance Receivables - Finance receivables categorized based on credit quality indicators (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($) item	Dec. 30, 2017 USD ($)
Finance receivables categorized based on the internally assigned credit quality
Number of loan categories based on key credit quality indicators for individual loan | item	3
Performing
Finance receivables categorized based on the internally assigned credit quality
Total finance receivables	$ 713	$ 733
Watchlist
Finance receivables categorized based on the internally assigned credit quality
Total finance receivables	41	56
Nonaccrual
Finance receivables categorized based on the internally assigned credit quality
Total finance receivables	$ 56	$ 61
Nonaccrual as a percentage of finance receivables	6.91%	7.18%
Minimum | Nonaccrual
Finance receivables categorized based on the internally assigned credit quality
Number of months of contractual delinquency to classify accounts as nonaccrual unless such collection is not doubtful	3 months