Goodwill and Intangible Assets, Net - Additional Information (Detail) € in Millions			1 Months Ended	3 Months Ended		12 Months Ended
	Jun. 22, 2016 EUR (€) Installment	Nov. 05, 2013 EUR (€)	Jul. 31, 2016 EUR (€)	Sep. 30, 2016 USD ($) Unit	Sep. 30, 2015 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2015 EUR (€)	Mar. 10, 2016 USD ($)
Goodwill [Line Items]
Goodwill				$ 1,511,380,000		$ 1,510,279,000
Goodwill, favorable foreign currency translation				1,200,000
Goodwill impairment charges				0	$ 0
Net intangible assets				461,843,000		476,284,000
Amortization expense of intangible assets				15,500,000	$ 21,100,000
Lifestyle Audio [Member]
Goodwill [Line Items]
Goodwill				$ 157,708,000		157,600,000
Number of reporting units | Unit				2
TowerSec Ltd. [Member]
Goodwill [Line Items]
Goodwill								$ 69,438,000
Increase (Decrease) in goodwill				$ 100,000
Innovative Systems GmbH [Member]
Goodwill [Line Items]
Dispute settlement amount | €		€ 16.3
Payments for partial award settlement | €							€ 16.3
Loss contingency settlement agreement date				Jun. 22, 2016
Percentage of shareholders involved in contingent purchase Price	80.05%
Loss contingency settlement agreement terms				Under the terms of the agreement, we will pay the 80.05% Shareholders €76.8 million (the “IS Obligation”), with an initial payment of €24.8 million which was paid in July 2016 and four installment payments of €13 million due every July 1st from 2017 through 2020.
Remaining disputed amount | €	€ 76.8
Remaining disputed amount, initial payment paid | €			€ 24.8
Number of installments after initial payment | Installment	4
Remaining disputed amount, each installment payable | €	€ 13.0
First installment due date				Jul. 01, 2017
Final installment due date				Jul. 01, 2020
Additional contingent purchase price						$ 74,500,000
Discount percentage on early installments	8.00%					8.00%
Disputes resolved shareholders percentage	19.95%