Amortization Expense Associated with Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Mar. 31, 2015		Mar. 31, 2014		Mar. 31, 2015		Mar. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Amortization expense of intangible assets	$ 3,515	[1]	$ 2,908	[1]	$ 6,447	[1]	$ 5,921	[1]
Cost of revenues
Finite-Lived Intangible Assets [Line Items]
Amortization expense of intangible assets	1,901		1,823		3,737		3,622
Selling, general and administrative expenses
Finite-Lived Intangible Assets [Line Items]
Amortization expense of intangible assets	$ 1,614		$ 1,085		$ 2,710		$ 2,299

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