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Investments - Amortized Cost, Unrealized Holding Gains and (Losses) and Fair Value of Available-for-sale Securities (Detail) - USD ($) $ in Thousands | Jun. 30, 2018 | Sep. 30, 2017
--- | --- | ---
Schedule Of Available For Sale Securities [Line Items] |  |
Amortized Cost | $ 34,814 | $ 31,817
Unrealized Losses | (54) | (15)
Fair Value | 34,760 | 31,802
Short-term commercial paper and corporate bonds [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Amortized Cost | 34,814 | 31,817
Unrealized Losses | (54) | (15)
Fair Value | $ 34,760 | $ 31,802

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- Definition Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading. + References No definition available. + Details
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- Definition Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale. + References No definition available. + Details
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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. + Details
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