Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Sep. 30, 2015
Assets:
Available-for-sale securities	$ 6,086	$ 133,308
Fair Value, Measurements, Recurring
Assets:
Cash equivalents	101	11,628
Available-for-sale securities	6,086	133,308
Foreign exchange contracts	22	89
Stock warrant	47	59
Total Assets	12,106	150,421
Liabilities
Contingent consideration	500	811
Foreign exchange contracts	204	36
Total Liabilities	704	847
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Recurring
Assets:
Cash equivalents	56	10,133
Available-for-sale securities	0	0
Foreign exchange contracts	0	0
Stock warrant	0	0
Total Assets	56	10,133
Liabilities
Contingent consideration	0	0
Foreign exchange contracts	0	0
Total Liabilities	0	0
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring
Assets:
Cash equivalents	45	1,495
Available-for-sale securities	6,086	133,308
Foreign exchange contracts	22	89
Stock warrant	0	0
Total Assets	6,153	134,892
Liabilities
Contingent consideration	0	0
Foreign exchange contracts	204	36
Total Liabilities	204	36
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring
Assets:
Cash equivalents	0	0
Available-for-sale securities	0	0
Foreign exchange contracts	0	0
Stock warrant	47	59
Total Assets	5,897	5,396
Liabilities
Contingent consideration	500	811
Foreign exchange contracts	0	0
Total Liabilities	500	811
Convertible Debt Securities | Fair Value, Measurements, Recurring
Assets:
Convertible debt securities	5,850	5,337
Convertible Debt Securities | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Recurring
Assets:
Convertible debt securities	0	0
Convertible Debt Securities | Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring
Assets:
Convertible debt securities	0	0
Convertible Debt Securities | Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring
Assets:
Convertible debt securities	$ 5,850	$ 5,337