Segment Reporting and Geographic Locations - Summary Composition by Product Category of Revenues (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue from External Customer [Line Items]
Revenues	$ 223,602	$ 225,010	$ 233,391	$ 215,734	$ 188,339	$ 198,349	$ 195,127	$ 173,416	$ 897,737	$ 755,231	$ 662,112
Seats and seating systems
Revenue from External Customer [Line Items]
Revenues									369,337	314,717	280,575
Electrical wire harnesses and panel assemblies
Revenue from External Customer [Line Items]
Revenues									196,411	189,154	149,417
Trim systems and components
Revenue from External Customer [Line Items]
Revenues									195,427	150,228	132,623
Cab structures and sleeper boxes
Revenue from External Customer [Line Items]
Revenues									76,380	56,417	57,605
Mirrors, wipers and controls
Revenue from External Customer [Line Items]
Revenues									$ 60,182	$ 44,715	$ 41,892
Product Concentration Risk | Revenues
Revenue from External Customer [Line Items]
Percent of net revenues (as a percent)									100.00%	100.00%	100.00%
Product Concentration Risk | Revenues | Seats and seating systems
Revenue from External Customer [Line Items]
Percent of net revenues (as a percent)									41.00%	42.00%	42.00%
Product Concentration Risk | Revenues | Electrical wire harnesses and panel assemblies
Revenue from External Customer [Line Items]
Percent of net revenues (as a percent)									22.00%	25.00%	23.00%
Product Concentration Risk | Revenues | Trim systems and components
Revenue from External Customer [Line Items]
Percent of net revenues (as a percent)									22.00%	20.00%	20.00%
Product Concentration Risk | Revenues | Cab structures and sleeper boxes
Revenue from External Customer [Line Items]
Percent of net revenues (as a percent)									9.00%	7.00%	9.00%
Product Concentration Risk | Revenues | Mirrors, wipers and controls
Revenue from External Customer [Line Items]
Percent of net revenues (as a percent)									6.00%	6.00%	6.00%