Related Party Transactions (Details)	9 Months Ended
	Sep. 30, 2024 USD ($) director $ / shares shares	Dec. 31, 2023 USD ($) shares
Related Party Transaction [Line Items]
Due from related party	$ 39,400,000	$ 63,800,000
Outstanding amounts due	$ 123,500,000	$ 99,500,000
Lemonade, Inc. | Affiliated entity | The Lemonade Foundation
Related Party Transaction [Line Items]
Shares owned by foundation (in shares) | shares	400,000	400,000
Related Party
Related Party Transaction [Line Items]
Number of shared directors | director	2
Contribution to the Lemonade Foundation (in shares) | shares	500,000
Contribution of common stock to related party, fair value (usd per share) | $ / shares	$ 24.36
Due from related party	$ 0	$ 0
Outstanding amounts due	$ 0	$ 0