Restructuring - Summary of Ongoing Restructuring Activities (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended		24 Months Ended
	Sep. 30, 2017	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Nov. 19, 2015
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred	$ 400	$ 2,013	$ 2,289	$ 4,300
Edgewood Wire Harness
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred	0	0		400
Piedmont Seating
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred	0	0		1,000
Monona Wire Harness
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred	0	1,000		600
Shadyside Stamping
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred	400	1,000		1,900
Other Restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred	0	0		400
Employee Costs
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred		212	$ 1,721
Employee Costs | Edgewood Wire Harness | Cost of Revenues
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred	0	0		300
Employee Costs | Piedmont Seating | Cost of Revenues
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred	0	0		600
Employee Costs | Monona Wire Harness | Cost of Revenues
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred	0	(400)		500
Employee Costs | Shadyside Stamping | Cost of Revenues
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred	200	600		1,700
Employee Costs | Other Restructuring | Cost of Revenues
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred	0	0		100
Employee Costs | Other Restructuring | Selling, general and administrative
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred	0	0		300
Facility and other costs | Edgewood Wire Harness | Cost of Revenues
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred	0	0		100
Facility and other costs | Piedmont Seating | Cost of Revenues
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred	0	0		400
Facility and other costs | Monona Wire Harness | Cost of Revenues
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred	0	1,400		100
Facility and other costs | Shadyside Stamping | Cost of Revenues
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred	$ 200	400		$ 200
Minimum
Restructuring Cost and Reserve [Line Items]
Expected Future Expense (Income)		200
Expected restructuring costs					$ 6,500
Minimum | Edgewood Wire Harness
Restructuring Cost and Reserve [Line Items]
Total Expense		400
Expected Future Expense (Income)		0
Minimum | Piedmont Seating
Restructuring Cost and Reserve [Line Items]
Total Expense		1,000
Expected Future Expense (Income)		0
Minimum | Monona Wire Harness
Restructuring Cost and Reserve [Line Items]
Total Expense		2,000
Expected Future Expense (Income)		400
Minimum | Shadyside Stamping
Restructuring Cost and Reserve [Line Items]
Total Expense		2,700
Expected Future Expense (Income)		(200)
Minimum | Other Restructuring
Restructuring Cost and Reserve [Line Items]
Total Expense		400
Expected Future Expense (Income)		0
Minimum | Employee Costs | Edgewood Wire Harness | Cost of Revenues
Restructuring Cost and Reserve [Line Items]
Total Expense		300
Expected Future Expense (Income)		0
Minimum | Employee Costs | Piedmont Seating | Cost of Revenues
Restructuring Cost and Reserve [Line Items]
Total Expense		600
Expected Future Expense (Income)		0
Minimum | Employee Costs | Monona Wire Harness | Cost of Revenues
Restructuring Cost and Reserve [Line Items]
Total Expense		100
Expected Future Expense (Income)		0
Minimum | Employee Costs | Shadyside Stamping | Cost of Revenues
Restructuring Cost and Reserve [Line Items]
Total Expense		2,500
Expected Future Expense (Income)		200
Minimum | Employee Costs | Other Restructuring | Cost of Revenues
Restructuring Cost and Reserve [Line Items]
Total Expense		100
Expected Future Expense (Income)		0
Minimum | Employee Costs | Other Restructuring | Selling, general and administrative
Restructuring Cost and Reserve [Line Items]
Total Expense		300
Expected Future Expense (Income)		0
Minimum | Facility and other costs | Edgewood Wire Harness | Cost of Revenues
Restructuring Cost and Reserve [Line Items]
Total Expense		100
Expected Future Expense (Income)		0
Minimum | Facility and other costs | Piedmont Seating | Cost of Revenues
Restructuring Cost and Reserve [Line Items]
Total Expense		400
Expected Future Expense (Income)		0
Minimum | Facility and other costs | Monona Wire Harness | Cost of Revenues
Restructuring Cost and Reserve [Line Items]
Total Expense		1,900
Expected Future Expense (Income)		400
Minimum | Facility and other costs | Shadyside Stamping | Cost of Revenues
Restructuring Cost and Reserve [Line Items]
Total Expense		200
Expected Future Expense (Income)		(400)
Maximum
Restructuring Cost and Reserve [Line Items]
Expected Future Expense (Income)		1,300
Expected restructuring costs					$ 7,600
Maximum | Edgewood Wire Harness
Restructuring Cost and Reserve [Line Items]
Total Expense		400
Expected Future Expense (Income)		0
Maximum | Piedmont Seating
Restructuring Cost and Reserve [Line Items]
Total Expense		1,000
Expected Future Expense (Income)		0
Maximum | Monona Wire Harness
Restructuring Cost and Reserve [Line Items]
Total Expense		2,400
Expected Future Expense (Income)		800
Maximum | Shadyside Stamping
Restructuring Cost and Reserve [Line Items]
Total Expense		3,400
Expected Future Expense (Income)		500
Maximum | Other Restructuring
Restructuring Cost and Reserve [Line Items]
Total Expense		400
Expected Future Expense (Income)		0
Maximum | Employee Costs | Edgewood Wire Harness | Cost of Revenues
Restructuring Cost and Reserve [Line Items]
Total Expense		300
Expected Future Expense (Income)		0
Maximum | Employee Costs | Piedmont Seating | Cost of Revenues
Restructuring Cost and Reserve [Line Items]
Total Expense		600
Expected Future Expense (Income)		0
Maximum | Employee Costs | Monona Wire Harness | Cost of Revenues
Restructuring Cost and Reserve [Line Items]
Total Expense		100
Expected Future Expense (Income)		0
Maximum | Employee Costs | Shadyside Stamping | Cost of Revenues
Restructuring Cost and Reserve [Line Items]
Total Expense		2,600
Expected Future Expense (Income)		300
Maximum | Employee Costs | Other Restructuring | Cost of Revenues
Restructuring Cost and Reserve [Line Items]
Total Expense		100
Expected Future Expense (Income)		0
Maximum | Employee Costs | Other Restructuring | Selling, general and administrative
Restructuring Cost and Reserve [Line Items]
Total Expense		300
Expected Future Expense (Income)		0
Maximum | Facility and other costs | Edgewood Wire Harness | Cost of Revenues
Restructuring Cost and Reserve [Line Items]
Total Expense		100
Expected Future Expense (Income)		0
Maximum | Facility and other costs | Piedmont Seating | Cost of Revenues
Restructuring Cost and Reserve [Line Items]
Total Expense		400
Expected Future Expense (Income)		0
Maximum | Facility and other costs | Monona Wire Harness | Cost of Revenues
Restructuring Cost and Reserve [Line Items]
Total Expense		2,300
Expected Future Expense (Income)		800
Maximum | Facility and other costs | Shadyside Stamping | Cost of Revenues
Restructuring Cost and Reserve [Line Items]
Total Expense		800
Expected Future Expense (Income)		$ 200