Investments - Summary of Fair Value of Investments Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Sep. 30, 2020
Assets
Short-term investments	$ 40,238	$ 40,035
Total assets at fair value	45,835	41,998
Liabilities
Acquisition-related contingent consideration	790	753
Total liabilities at fair value	790	753
U.S. Treasury
Assets
Short-term investments	9,571	10,283
Long-term investments	2,745	0
Asset-backed securities
Assets
Short-term investments	3,935	4,759
Long-term investments	962
Corporate debt securities | Financial
Assets
Short-term investments	6,387	7,695
Long-term investments	0	977
Corporate debt securities | Industrial
Assets
Short-term investments	1,913	1,924
Long-term investments	1,890	986
Commercial paper | Financial
Assets
Short-term investments	12,488	13,479
Commercial paper | Industrial
Assets
Short-term investments	5,944	1,895
Quoted Prices in Active Markets (Level 1)
Assets
Short-term investments	9,571	10,283
Total assets at fair value	12,316	10,283
Liabilities
Acquisition-related contingent consideration	0	0
Total liabilities at fair value	0	0
Quoted Prices in Active Markets (Level 1) | U.S. Treasury
Assets
Short-term investments	9,571	10,283
Long-term investments	2,745	0
Quoted Prices in Active Markets (Level 1) | Asset-backed securities
Assets
Short-term investments	0	0
Long-term investments	0
Quoted Prices in Active Markets (Level 1) | Corporate debt securities | Financial
Assets
Short-term investments		0
Long-term investments		0
Quoted Prices in Active Markets (Level 1) | Corporate debt securities | Industrial
Assets
Short-term investments		0
Long-term investments		0
Quoted Prices in Active Markets (Level 1) | Commercial paper | Financial
Assets
Short-term investments		0
Quoted Prices in Active Markets (Level 1) | Commercial paper | Industrial
Assets
Short-term investments		0
Significant Other Observable Inputs (Level 2)
Assets
Short-term investments	30,667	29,752
Total assets at fair value	33,519	31,715
Liabilities
Acquisition-related contingent consideration	0	0
Total liabilities at fair value	0	0
Significant Other Observable Inputs (Level 2) | U.S. Treasury
Assets
Short-term investments	0	0
Long-term investments	0	0
Significant Other Observable Inputs (Level 2) | Asset-backed securities
Assets
Short-term investments	3,935	4,759
Long-term investments	962
Significant Other Observable Inputs (Level 2) | Corporate debt securities | Financial
Assets
Short-term investments	6,387	7,695
Long-term investments	0	977
Significant Other Observable Inputs (Level 2) | Corporate debt securities | Industrial
Assets
Short-term investments	1,913	1,924
Long-term investments	1,890	986
Significant Other Observable Inputs (Level 2) | Commercial paper | Financial
Assets
Short-term investments	12,488	13,479
Significant Other Observable Inputs (Level 2) | Commercial paper | Industrial
Assets
Short-term investments	5,944	1,895
Significant Unobservable Inputs (Level 3)
Assets
Short-term investments	0	0
Total assets at fair value	0	0
Liabilities
Acquisition-related contingent consideration	790	753
Total liabilities at fair value	790	753
Significant Unobservable Inputs (Level 3) | U.S. Treasury
Assets
Short-term investments	0	0
Long-term investments	0	0
Significant Unobservable Inputs (Level 3) | Asset-backed securities
Assets
Short-term investments	0	0
Long-term investments	0
Significant Unobservable Inputs (Level 3) | Corporate debt securities | Financial
Assets
Short-term investments	0	0
Long-term investments		0
Significant Unobservable Inputs (Level 3) | Corporate debt securities | Industrial
Assets
Short-term investments	0	0
Long-term investments		0
Significant Unobservable Inputs (Level 3) | Commercial paper | Financial
Assets
Short-term investments	0	0
Significant Unobservable Inputs (Level 3) | Commercial paper | Industrial
Assets
Short-term investments	$ 0	$ 0