Investments - Schedule of Investments' Gross Unrealized Loss and Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Sep. 30, 2019
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	$ 0	$ 5,073
Unrealized Losses, Less than 12 Months	0	(9)
Fair Value, 12 Months or More	8,051	0
Unrealized Losses, 12 Months or More	(47)	0
Fair Value	8,051	5,073
Unrealized Losses	(47)	(9)
U.S. Treasury securities, obligations of U.S. Government agencies and municipalities
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	0	3,993
Unrealized Losses, Less than 12 Months	0	(7)
Fair Value, 12 Months or More	7,053	0
Unrealized Losses, 12 Months or More	(39)	0
Fair Value	7,053	3,993
Unrealized Losses	(39)	(7)
Corporate debt
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	0	1,080
Unrealized Losses, Less than 12 Months	0	(2)
Fair Value, 12 Months or More	998	0
Unrealized Losses, 12 Months or More	(8)	0
Fair Value	998	1,080
Unrealized Losses	$ (8)	$ (2)

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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