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, 2015	Sep. 30, 2014	Jun. 30, 2015
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	14.00%	15.00%
Sales Revenue, Net [Member] | Fiat Chrysler Automobiles [Member]
Concentration Risk [Line Items]
Concentration risk percentage	15.00%	14.00%
Sales Revenue, Net [Member] | The Volkswagen Group [Member]
Concentration Risk [Line Items]
Concentration risk percentage	12.00%	11.00%
Sales Revenue, Net [Member] | Other Customers [Member]
Concentration Risk [Line Items]
Concentration risk percentage	59.00%	60.00%
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	11.00%		9.00%
Accounts Receivable [Member] | Fiat Chrysler Automobiles [Member]
Concentration Risk [Line Items]
Concentration risk percentage	13.00%		14.00%
Accounts Receivable [Member] | The Volkswagen Group [Member]
Concentration Risk [Line Items]
Concentration risk percentage	7.00%		7.00%
Accounts Receivable [Member] | Other Customers [Member]
Concentration Risk [Line Items]
Concentration risk percentage	69.00%		70.00%