Fair value measurement - Cash And Cash Equivalents And Available For Sale Securities At Fair Value (Detail) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Cash And Cash Equivalents At Amortized Cost	$ 46,735	$ 80,757
Available-for-sale Securities, Amortized Cost Basis	91,323
Cash And Cash Equivalents And Short Term Invesmtnets Amortized Cost	138,058	80,757
Available-for-sale Securities, Gross Unrealized Gain	49
Available for sale Securities Gross Unrealized Gain Loss	49
Cash and Cash Equivalents, at Carrying Value	46,735	80,757	$ 31,227
Short-term Investments	91,372
Cash, Cash Equivalents, and Short-term Investments	$ 138,107	$ 80,757

Available-for-sale Securities, Gross Unrealized Gain (Loss), Total

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- Definition

Cash And Cash Equivalents And Short Term Invesmtnets Amortized Cost

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- Definition

Cash And Cash Equivalents At Amortized Cost

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No definition available.

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- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

No definition available.

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- Definition

Amount of unrealized gain before deducting unrealized loss on investments in debt and equity securities classified as available-for-sale securities.

+ References

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-Publisher FASB
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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

+ References

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Cash includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the customer may deposit additional funds at any time and effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid Investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. Short-term investments, exclusive of cash equivalents, generally consist of marketable securities intended to be sold within one year (or the normal operating cycle if longer) and may include trading securities, available-for-sale securities, or held-to-maturity securities (if maturing within one year), as applicable.

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Amount of investments including trading securities, available-for-sale securities, held-to-maturity securities, and short-term investments classified as other and current.

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