Related Party Transactions (Details)		3 Months Ended		9 Months Ended		12 Months Ended
	Jan. 14, 2021 shares	Sep. 30, 2022 USD ($) director	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($) director $ / shares shares	Sep. 30, 2021 USD ($)	Dec. 31, 2020 shares	Dec. 31, 2021 USD ($)
Related Party Transaction [Line Items]
Due to (from) related parties		$ 0		$ 0			$ 0
Follow On Offering, Selling Shareholders
Related Party Transaction [Line Items]
Common stock sold (in shares) | shares	1,524,314
The Lemonade Foundation | Follow On Offering, Selling Shareholders
Related Party Transaction [Line Items]
Common stock sold (in shares) | shares	100,000
Affiliated entity | The Lemonade Foundation
Related Party Transaction [Line Items]
Number of shared directors | director		2		2
Contribution to the Lemonade Foundation (in shares) | shares				500,000		500,000
Contribution of common stock to related party, fair value (usd per share) | $ / shares				$ 24.36
Due from related party		$ 0		$ 0
Travel related expenses | Key stockholder
Related Party Transaction [Line Items]
Expenses with related parties (less than)		100,000	$ 100,000	100,000	$ 100,000
Rental expense | Affiliated entity
Related Party Transaction [Line Items]
Expenses with related parties (less than)		$ 100,000	$ 100,000	$ 100,000	$ 100,000