Description of Business and Summary of Significant Accounting Policies - Cash and cash equivalents (Details) $ in Millions	Mar. 31, 2024 USD ($) state	Dec. 31, 2023 USD ($) state
Accounting Policies [Abstract]
Restricted cash equivalents	$ 27.7
Restricted cash pledged against obligations to policyholders and creditors	1.4	$ 1.3
Restricted funds held for payment of possible warranty claims	$ 6.8	$ 7.3
Number of states regulatory guidelines of warranty claims | state	21	19
Indemnification hold back cost	$ 1.0	$ 1.9
Restricted cash pledged as collateral		$ 28.3