Investments - Additional Information (Details) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2024 USD ($) Security	Dec. 31, 2023 Security
Debt Securities, Available-for-sale [Line Items]
Number of securities in unrealized loss position | Security	31	28
Proceeds from sale of investment in fixed maturity securities	$ 1
Maximum investment maturity period	5 years	5 years
Investments on deposit with the state insurance department	$ 4