Summary of Significant Accounting Policies and Select Balance Sheet Information - Additional Information (Detail) - USD ($) shares in Millions	3 Months Ended		12 Months Ended
	Sep. 30, 2015	Mar. 31, 2013	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2006	Jan. 08, 2016	Nov. 20, 2015	Nov. 10, 2015
Summary Of Significant Accounting Policies [Line Items]
Net unrealized loss reclassified out of accumulated other comprehensive income with a corresponding adjustment to other income (loss)			$ 0	$ 0	$ 0
Held-to-maturity debt securities			0	0
Realized gains or losses on sales of available-for-sale securities			0	0
Realized gains on sales of available-for-sale securities					500,000
Realized losses on sales of available-for-sale securities					(100,000)
Depreciation expense			3,000,000	2,300,000	2,000,000
Impairment loss on investment			0
Transfer to Investments			2,000
Gain on sale of investment			43,000	514,000	492,000
Amortization expense			2,600,000	2,400,000	800,000
Other impairment losses			0
Goodwill	$ 8,010,000		27,282,000	26,555,000	8,010,000
Goodwill impairment charges			0
Additions to goodwill				17,892,000
Goodwill subject to revaluation due to fluctuations in exchange rates			13,400,000
Impairment charges relating to long-lived assets			0	0	0
Taxes collected from customers and remitted to governmental authorities			$ 100,000	$ 100,000	100,000
Discontinued operations used operating cash					45,000
Cash generated from financing activities					$ 45,000
Weighted average diluted shares outstanding excluded outstanding stock options			0.2	0.7	0.5
SurModics Pharmaceuticals [Member]
Summary Of Significant Accounting Policies [Line Items]
Discontinued operations activity			$ 0	$ 0
IDA [Member]
Summary Of Significant Accounting Policies [Line Items]
Reimbursement recorded as reduction to R&D expense			800,000	0	$ 0
Other Accrued Liabilities, Current and Other Long-term Liabilities [Member]
Summary Of Significant Accounting Policies [Line Items]
Current and non-current deferred revenue			$ 300,000	$ 400,000
Customer Concentration Risk [Member] | Revenue [Member] | Medtronic [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of revenue			18.00%	25.00%	26.00%
Medical Device [Member]
Summary Of Significant Accounting Policies [Line Items]
Goodwill			$ 19,272,000	$ 18,545,000
Additions to goodwill				17,892,000
Customer Lists [Member]
Summary Of Significant Accounting Policies [Line Items]
Intangible assets, acquired				12,600,000	$ 300,000
Non-compete [Member]
Summary Of Significant Accounting Policies [Line Items]
Intangible assets, acquired					200,000
Other Intangible Assets [Member]
Summary Of Significant Accounting Policies [Line Items]
Intangible assets, acquired					100,000
Developed Technology [Member]
Summary Of Significant Accounting Policies [Line Items]
Intangible assets, acquired				8,700,000
In-Process Research and Development [Member]
Summary Of Significant Accounting Policies [Line Items]
Intangible assets, acquired				$ 1,000,000
Creagh Medical Ltd [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of shares acquired				100.00%				100.00%
Goodwill			13,440,000
NorMedix, Inc. [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of shares acquired				100.00%			100.00%
Goodwill			4,452,000
Other Income, Net [Member]
Summary Of Significant Accounting Policies [Line Items]
Gain on sale of investment					500,000
Selling, General and Administrative Expenses [Member] | Trade Names [Member]
Summary Of Significant Accounting Policies [Line Items]
Impairment loss			100,000
Research and development [Member] | In-Process Research and Development [Member]
Summary Of Significant Accounting Policies [Line Items]
Impairment loss			300,000
ViaCyte, Inc. [Member]
Summary Of Significant Accounting Policies [Line Items]
Impairment loss on investment		$ 100,000				$ 4,700,000
Equity method investment			5,300,000
Cost method of investment			500,000
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Revenue recognized from activity with companies in which it had strategic investment			$ 100,000	$ 100,000	100,000
Product sales payment terms			45 days
Maximum [Member] | SurModics Pharmaceuticals [Member]
Summary Of Significant Accounting Policies [Line Items]
Discontinued operations used operating cash					100,000
Cash generated from financing activities					$ 100,000
Maximum [Member] | Other Accrued Liabilities [Member]
Summary Of Significant Accounting Policies [Line Items]
Liability recorded for customer royalty overpayments			$ 100,000	900,000
Maximum [Member] | Customer Concentration Risk [Member] | Revenue [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of revenue			10.00%
Maximum [Member] | Product Concentration Risk [Member] | Revenue [Member] | Medtronic [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of revenue			4.00%
Maximum [Member] | Selling, General and Administrative Expenses [Member] | In-Process Research and Development [Member]
Summary Of Significant Accounting Policies [Line Items]
Impairment loss				100,000
Maximum [Member] | ViaCyte, Inc. [Member]
Summary Of Significant Accounting Policies [Line Items]
Company's ownership percentage			1.00%
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Product sales payment terms			30 days
Minimum [Member] | Royalties [Member] | Revenue from Rights Concentration Risk [Member] | Revenue, Rights Granted [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of revenue			90.00%
CeloNova BioSciences, Inc. [Member]
Summary Of Significant Accounting Policies [Line Items]
Gross value of business acquired									$ 70,000,000
Impairment loss on investment	$ 1,500,000			0
Equity method investment			$ 0	$ 0
CeloNova BioSciences, Inc. [Member] | Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Company's ownership percentage			2.00%