Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Current assets
Cash and cash equivalents	$ 464.6	$ 69.4
Restricted cash	6.9	2.9
Short-term investments:	0.0	461.8
Prepaid expenses	7.9	9.8
Other current assets	0.8	1.6
Total current assets	480.2	545.5
Property and equipment, net	57.6	11.5
Intangible assets, net	0.4	0.4
Right-of-use assets	8.9	11.9
Other long-term assets	7.2	4.5
Total assets	554.3	573.8
Current liabilities
Accounts payable	14.3	3.6
Current portion of lease liabilities	2.8	3.7
Current portion of notes payable	0.0	9.3
Accrued expenses and other current liabilities	96.9	36.7
Total current liabilities	114.0	53.3
Notes payable, net of current portion	7.2	0.0
Lease liabilities, net of current portion	13.2	9.2
Warrant liabilities	39.9	7.0
Other long-term liabilities	12.9	11.0
Total liabilities	187.2	80.5
Commitments and contingencies (Note 8)
Stockholders’ equity
Preferred stock, $0.0001 par value; 10,000,000 shares authorized; no shares issued and outstanding as of December 31, 2023 and 2022	0.0	0.0
Additional paid-in capital	1,515.9	1,185.0
Accumulated deficit	(1,148.8)	(690.9)
Accumulated other comprehensive loss	0.0	(0.8)
Total stockholders’ equity	367.1	493.3
Total liabilities and stockholders’ equity	554.3	573.8
Class A
Stockholders’ equity
Common stock, value, issued	0.0	0.0
Class B
Stockholders’ equity
Common stock, value, issued	$ 0.0	$ 0.0