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Marketable Securities - Company's Assets Measured at Fair Value (Detail) - USD ($)	Mar. 31, 2016	Sep. 30, 2015
Investment Holdings [Line Items]
Total	$ 85,048,000	$ 84,357,000
Equities [Member]
Investment Holdings [Line Items]
Total	6,170,000	20,915,000
Mutual Funds [Member]
Investment Holdings [Line Items]
Total	6,572,000	11,885,000
Exchange Traded Funds [Member]
Investment Holdings [Line Items]
Total	1,040,000	4,086,000
Government Securities [Member]
Investment Holdings [Line Items]
Total	29,998,000	43,883,000
Cash and Money Funds [Member]
Investment Holdings [Line Items]
Total	41,268,000	3,588,000
Level 1 [Member]
Investment Holdings [Line Items]
Total	85,048,000	84,357,000
Level 1 [Member] | Equities [Member]
Investment Holdings [Line Items]
Total	6,170,000	20,915,000
Level 1 [Member] | Mutual Funds [Member]
Investment Holdings [Line Items]
Total	6,572,000	11,885,000
Level 1 [Member] | Exchange Traded Funds [Member]
Investment Holdings [Line Items]
Total	1,040,000	4,086,000
Level 1 [Member] | Government Securities [Member]
Investment Holdings [Line Items]
Total	29,998,000	43,883,000
Level 1 [Member] | Cash and Money Funds [Member]
Investment Holdings [Line Items]
Total	$ 41,268,000	$ 3,588,000

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Amount of investments in debt and equity securities, including, but not limited to, held-to-maturity, trading and available-for-sale expected to be converted to cash, sold or exchanged within one year or the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=28358313&loc=d3e6676-107765

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=49167202&loc=d3e26626-111562

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.2)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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