Goodwill and Intangible Assets - Amortization Expense Associated with Intangible Assets (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Mar. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Amortization expense of intangible assets	[1]	$ 3,507	$ 3,515	$ 7,087	$ 6,447
Cost of revenues
Finite-Lived Intangible Assets [Line Items]
Amortization expense of intangible assets		1,840	1,901	3,747	3,737
Selling, general and administrative expenses
Finite-Lived Intangible Assets [Line Items]
Amortization expense of intangible assets		$ 1,667	$ 1,614	$ 3,340	$ 2,710

[1] Cost of revenues and selling, general and administrative expenses exclude the amortization of intangible assets. See Note 5.