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Investments - Schedule of Investments to be Available-for-sale (Detail) - USD ($) $ in Thousands | Sep. 30, 2018 | Sep. 30, 2017
--- | --- | ---
Schedule Of Available For Sale Securities [Line Items] |  |  |
Amortized Cost |  | $ 46,623 |
Gross Unrealized (Loss) |  | (1,204) |
Fair Value | [1] | 45,419 | $ 11,777
Cash and Receivables |  |  |
Schedule Of Available For Sale Securities [Line Items] |  |  |
Amortized Cost |  | 350 |
Fair Value |  | 350 |
U.S. Government Sponsored Agencies |  |  |
Schedule Of Available For Sale Securities [Line Items] |  |  |
Amortized Cost |  | 10,735 |
Gross Unrealized (Loss) |  | (192) |
Fair Value |  | 10,543 |
Corporate Debt Securities |  |  |
Schedule Of Available For Sale Securities [Line Items] |  |  |
Amortized Cost |  | 30,427 |
Gross Unrealized (Loss) |  | (928) |
Fair Value |  | 29,499 |
Foreign Bonds and Notes |  |  |
Schedule Of Available For Sale Securities [Line Items] |  |  |
Amortized Cost |  | 5,111 |
Gross Unrealized (Loss) |  | (84) |
Fair Value |  | $ 5,027 |
[1] | See Note 2 - Investments.

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