Significant Customers - Schedule of Percentage of Net Sales and Net Accounts Receivable Due from Customers (Detail) - Customer Concentration Risk [Member]	3 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Jun. 30, 2016
Sales Revenue, Net [Member]
Concentration Risk [Line Items]
Concentration risk percentage	100.00%	100.00%
Sales Revenue, Net [Member] | BMW [Member]
Concentration Risk [Line Items]
Concentration risk percentage	13.00%	14.00%
Sales Revenue, Net [Member] | Fiat Chrysler Automobiles [Member]
Concentration Risk [Line Items]
Concentration risk percentage	15.00%	15.00%
Sales Revenue, Net [Member] | The Volkswagen Group [Member]
Concentration Risk [Line Items]
Concentration risk percentage	12.00%	15.00%
Sales Revenue, Net [Member] | Other Customers [Member]
Concentration Risk [Line Items]
Concentration risk percentage	60.00%	56.00%
Accounts Receivable [Member]
Concentration Risk [Line Items]
Concentration risk percentage	100.00%		100.00%
Accounts Receivable [Member] | BMW [Member]
Concentration Risk [Line Items]
Concentration risk percentage	9.00%		9.00%
Accounts Receivable [Member] | Fiat Chrysler Automobiles [Member]
Concentration Risk [Line Items]
Concentration risk percentage	17.00%		17.00%
Accounts Receivable [Member] | The Volkswagen Group [Member]
Concentration Risk [Line Items]
Concentration risk percentage	8.00%		9.00%
Accounts Receivable [Member] | Other Customers [Member]
Concentration Risk [Line Items]
Concentration risk percentage	66.00%		65.00%