Allowance for Doubtful Accounts (Tables)
 12 Months Ended
Dec. 28, 2019
Receivables [Abstract]  
Summary of Activity in Allowance for Doubtful Accounts
A summary of the activity in the allowance for doubtful accounts for the last three fiscal years is as follows:
 
2019
 
2018
 
2017
Balance as of beginning of year
$
29

 
$
26

 
$
25

Charged to costs and expenses
21

 
17

 
18

Customer accounts written off—net of recoveries
(20
)
 
(14
)
 
(17
)
Balance as of end of year
$
30

 
$
29

 
$
26