Cash and Receivables Allowance for Doubtful Accounts Receivable (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 28, 2020	Jun. 30, 2019
Allowance for Doubtful Accounts
Balance at beginning of period; accounts receivable	$ 3,314	$ 4,940
Provision for doubtful accounts; accounts receivable	1,156	(754)
Uncollectible accounts written off, net of recoveries; accounts receivable	(66)	(139)
Balance at end of period; accounts receivable	4,404	4,047
Balance at beginning of period; notes receivable	6,705	2,000
Provision for doubtful accounts; notes receivable	(8)	1,843
Uncollectible accounts written off, net of recoveries; notes receivable	(1,192)	7
Balance at end of period; notes receivable	5,505	3,850
Balance at beginning of period; total	10,019	6,940
Provision for doubtful accounts; total	1,148	1,089
Uncollectible accounts written off, net of recoveries; total	(1,258)	(132)
Balance at end of period; total	$ 9,909	$ 7,897