Marketable Securities (Schedule of Fair Value and Gross Unrealized Losses) (Details) - Corporate notes/bonds - USD ($) $ in Thousands	Sep. 30, 2020	Sep. 30, 2019
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 9,841	$ 12,419
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(17)	(14)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	0	16,369
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	(14)
Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value	9,841	28,788
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ (17)	$ (28)

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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