Income Taxes - Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Sep. 30, 2015
Deferred tax assets:
Net operating loss carryforward	$ 16,122	$ 17,650
Foreign tax credit carryforward	14,590	0
Research credit carryforward	6,132	5,759
Accrued bonus	13,807	5,400
Investments	619	1,042
Accrued compensation	1,328	1,834
Share-based compensation	27,203	23,741
Deferred revenue	1,467	979
Accrued lease costs	3,406	5,009
Property and equipment	3,348	3,249
Other	7,728	5,613
Deferred tax assets, gross	95,750	70,276
Less valuation allowance	(15,145)	(13,882)
Total deferred tax assets	80,605	56,394
Deferred tax liabilities:
Intangible assets	(28,056)	(30,286)
Prepaid expense	(3,959)	(3,877)
Other	(992)	(993)
Total deferred tax liabilities	(33,007)	(35,156)
Deferred tax assets, net	$ 47,598	$ 21,238