Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Income Taxes [Line Items]
Foreign pretax earnings	$ 43,300,000	$ 24,300,000	$ 26,900,000
Current foreign tax expense related to foreign tax withholdings	7,700,000	4,800,000	6,300,000
U.S. federal statutory income tax rate	35.00%	35.00%	35.00%
Excess amount for financial reporting over tax basis of investments in foreign subsidiaries	49,900,000
Unrecognized tax benefits	4,554,000	9,009,000	7,501,000	9,539,000
Unrecognized tax benefits that would impact the effective tax rate if recognized	3,900,000
Uncertain tax benefits will occur in the next 12 months	1,200,000
Unrecognized tax benefits, accrued interest	500,000
U.S. federal
Income Taxes [Line Items]
Net operating loss carryforwards	29,000,000
Net operating loss carryforwards expiration dates	2024
State
Income Taxes [Line Items]
Net operating loss carryforwards	300,000
Net operating loss carryforwards expiration dates	2021
Foreign NOL carryforwards
Income Taxes [Line Items]
Net operating loss carryforwards	36,300,000
CA state research credit
Income Taxes [Line Items]
Excess state research credit	5,000,000
Valuation allowance	$ 5,000,000