Revenue Recognition - Summary of Disaggregated Net Sales (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Apr. 01, 2017
Disaggregation Of Revenue [Line Items]
Net Sales	$ 227,262	$ 221,625
U.S. Customers [Member]
Disaggregation Of Revenue [Line Items]
Net Sales	210,426	208,582
Non-U.S. Customers [Member]
Disaggregation Of Revenue [Line Items]
Net Sales	16,836	13,043
Powertrain [Member]
Disaggregation Of Revenue [Line Items]
Net Sales	95,152	94,863
Chassis [Member]
Disaggregation Of Revenue [Line Items]
Net Sales	66,999	55,484
Automotive Body [Member]
Disaggregation Of Revenue [Line Items]
Net Sales	55,244	61,475
Hardware [Member]
Disaggregation Of Revenue [Line Items]
Net Sales	$ 9,867	$ 9,803