Preproduction Costs Related to Long-Term Supply Arrangements - Summary of Unamortized Customer-Owned Tooling Costs Included in Non-current Assets and Deferred Tooling Revenues Included in Accrued Expenses and Other Non-current Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Customer-Owned Tooling Costs
Preproduction costs	$ 97,410	$ 84,198
Accumulated amortization	(78,149)	(71,409)
Net preproduction costs	19,261	12,789
Deferred Tooling Revenues
Accrued expenses	5,318	4,654
Other non-current liabilities	6,598	1,974
Total deferred tooling revenues	$ 11,916	$ 6,628