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Captive Insurance Collateral - Schedule of Captive Insurance Collateral to be Available-for-sale Investments (Detail) - USD ($) $ in Thousands | Sep. 30, 2020 | Sep. 30, 2019
--- | --- | ---
Schedule Of Available For Sale Securities [Line Items] |  |
Amortized Cost | $ 67,842 | $ 57,461
Gross Unrealized Gain | 1,971 | 1,032
Gross Unrealized (Loss) | (26) | (3)
Fair Value | 69,787 | 58,490
Cash and Receivables |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Amortized Cost | 1,152 | 509
Fair Value | 1,152 | 509
U.S. Government Sponsored Agencies |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Amortized Cost | 42,032 | 29,055
Gross Unrealized Gain | 229 | 198
Gross Unrealized (Loss) | (26) | (3)
Fair Value | 42,235 | 29,250
Corporate Debt Securities |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Amortized Cost | 21,666 | 23,831
Gross Unrealized Gain | 1,660 | 773
Fair Value | 23,326 | 24,604
Foreign Bonds and Notes |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Amortized Cost | 2,992 | 4,066
Gross Unrealized Gain | 82 | 61
Fair Value | $ 3,074 | $ 4,127

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- Definition Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27161-111563 + Details
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