Business Combination - Narrative (Details) $ / shares in Units, $ in Millions		3 Months Ended
	Nov. 08, 2021 USD ($) tradingDay $ / shares	Mar. 31, 2022 USD ($) tradingDay $ / shares	Mar. 31, 2021	Dec. 31, 2021 $ / shares
Business Combination, Separately Recognized Transactions [Line Items]
Business combination converted exchange ratio			1.01547844
Common stock par value (in dollars per share) | $ / shares		$ 0.0001		$ 0.0001
Trading days | tradingDay		20
Lemonade, Inc.
Business Combination, Separately Recognized Transactions [Line Items]
Common stock par value (in dollars per share) | $ / shares	$ 0.00001
Metromile, Inc. | Lemonade, Inc.
Business Combination, Separately Recognized Transactions [Line Items]
Fully diluted equity value	$ 500.0
Equity value, net of unrestricted cash and cash equivalents	$ 340.0
Business combination converted exchange ratio	0.05263
Common stock par value (in dollars per share) | $ / shares	$ 0.00001
Trading days | tradingDay	20
Number of trading days prior to conversion | tradingDay	3
Transaction costs		$ 3.8
Transaction related costs		$ 0.3