Revenue Recognition - Summary of Disaggregated Net Sales (Detail) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 29, 2018	[1]	Sep. 29, 2018	[1]	Jun. 30, 2018	[1]	Mar. 31, 2018	[1]	Dec. 30, 2017	Sep. 30, 2017	Jul. 01, 2017	Apr. 01, 2017	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Disaggregation Of Revenue [Line Items]
Net Sales	$ 260,341		$ 247,954		$ 238,147		$ 227,262		$ 227,719	$ 224,615	$ 229,262	$ 221,625	$ 973,705	$ 903,221	$ 859,604
U.S. Customers [Member]
Disaggregation Of Revenue [Line Items]
Net Sales													913,181	847,394	810,969
Non-U.S. Customers [Member]
Disaggregation Of Revenue [Line Items]
Net Sales													60,524	55,827	48,635
Powertrain [Member]
Disaggregation Of Revenue [Line Items]
Net Sales													393,979	374,372	351,423
Chassis [Member]
Disaggregation Of Revenue [Line Items]
Net Sales													278,584	238,239	218,645
Automotive Body [Member]
Disaggregation Of Revenue [Line Items]
Net Sales													256,344	245,869	244,465
Hardware [Member]
Disaggregation Of Revenue [Line Items]
Net Sales													$ 44,798	$ 44,741	$ 45,071

[1] Quarterly information does not add to year to date information due to rounding