Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
SEC Schedule, 12-09, Allowance, Credit Loss [Member]
Year ended:
Balance at beginning of year		$ 133	$ 107	$ 470
Charged to costs and expenses		162	70	38
Charged to other accounts		0	0	0
Deductions	[1]	121	44	401
Balance at end of year		174	133	107
Provision for claims, allowances and warranties [Member]
Year ended:
Balance at beginning of year		6,360	7,039	6,658
Charged to costs and expenses		2,098	8,341	10,407
Charged to other accounts		0	0	0
Deductions	[2]	2,741	9,020	10,026
Balance at end of year		$ 5,717	$ 6,360	$ 7,039

[1] Uncollectible accounts written off, net of recoveries.

[2] Reserve reductions for claims, allowances and warranties settled.