Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Revenue:
Total revenue	$ 22,822	$ 22,676	$ 45,438	$ 44,917
Operating costs and expenses:
Type of Cost, Good or Service [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember
Product costs	$ 3,769	$ 3,093	$ 6,972	$ 6,616
Research and development	11,935	13,555	24,077	25,041
Selling, general and administrative	6,733	4,876	13,676	10,825
Acquired intangible asset amortization	541	604	1,135	1,210
Contingent consideration gain		(317)		(352)
Total operating costs and expenses	22,978	21,811	45,860	43,340
Operating (loss) income	(156)	865	(422)	1,577
Other (expense) income:
Investment income, net	210	265	460	581
Interest expense	(30)	(37)	(70)	(74)
Foreign exchange (loss) gain	(30)	5	(77)	141
Impairment loss on strategic investment	(479)		(479)
Other		2	1	9
Other (expense) income	(329)	235	(165)	657
(Loss) income before income taxes	(485)	1,100	(587)	2,234
Income tax benefit	1,947	162	2,197	338
Net income	$ 1,462	$ 1,262	$ 1,610	$ 2,572
Basic net income per share	$ 0.11	$ 0.09	$ 0.12	$ 0.19
Diluted net income per share	$ 0.11	$ 0.09	$ 0.12	$ 0.19
Weighted average number of shares outstanding:
Basic	13,507	13,390	13,474	13,379
Diluted	13,751	13,785	13,779	13,816
Product Sales [Member]
Revenue:
Total revenue	$ 11,770	$ 9,887	$ 21,744	$ 19,638
Royalties and License Fees [Member]
Revenue:
Total revenue	8,221	9,932	18,369	20,028
Research, Development and Other [Member]
Revenue:
Total revenue	$ 2,831	$ 2,857	$ 5,325	$ 5,251