Investments - Additional Information (Details) $ in Millions	3 Months Ended
Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($) Security	Sep. 30, 2022 Security
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Debt Securities	$ 29.1	$ 28.8
Available-for-sale Debt Securities	3.7	$ 6.4
Number of securities in unrealized loss position \| Security		33	31
Proceeds from sale of investment in fixed maturity securities and maturing time deposits	3.7
Payments to acquire investments	3.6
Investments on deposit with the state insurance department	4.2
U.S. Treasury securities, obligations of U.S. Government agencies and municipalities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Debt Securities	22.3	$ 21.0
Corporate Debt Securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Debt Securities	6.8	7.8
Bank Time Deposits
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Debt Securities	$ 5.6	$ 5.6

Carrying amount of cash and investment securities on deposit with state regulatory authorities in connection with capital requirements.

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