Summary of Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2023 USD ($) segment	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of reportable segments | segment	1
Premium receivable, allowance for doubtful accounts	$ 2,500,000	$ 2,700,000
Amortization of net deferred acquisition costs	21,800,000	17,000,000	$ 9,500,000
Goodwill, impairment loss	0
Matching contributions	2,600,000	2,200,000	900,000
Advertising expenses	$ 55,200,000	$ 88,500,000	$ 104,600,000
Options to purchase common stock
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Requisite service period	4 years
Internal use software
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful life	2 years