REVISION OF PREVIOUSLY ISSUED QUARTERLY FINANCIAL STATEMENTS (UNAUDITED) - Income Statement (Details) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended				6 Months Ended	9 Months Ended	12 Months Ended
	Aug. 12, 2022	Dec. 31, 2022 USD ($) $ / shares shares	Sep. 30, 2022 USD ($) $ / shares shares	Jun. 30, 2022 USD ($) $ / shares shares	Mar. 31, 2022 USD ($) $ / shares shares	Jun. 30, 2022 USD ($) $ / shares shares	Sep. 30, 2022 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares		Dec. 31, 2021 USD ($) $ / shares shares		Dec. 31, 2020 USD ($) $ / shares shares
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Sales and marketing		$ 3.2	$ 8.1	$ 21.4	$ 15.3	$ 36.7	$ 44.8	$ 48.0		$ 270.2		$ 139.7
General and administrative		31.0	26.4	39.5	30.5	70.0	96.4	127.4		97.6		78.5
Total operating expenses		119.0	130.8	166.7	157.4	324.1	454.9	573.9		830.6		632.1
Operating loss		(47.7)	(57.1)	(86.3)	(72.0)	(158.3)	(215.4)	(263.1)		(485.2)		(285.3)
Loss before income taxes		(58.3)	(66.4)	(95.5)	(77.5)	(173.0)	(239.4)	(297.7)		(521.1)		(363.0)
Net loss		(58.3)	(66.4)	(95.5)	(77.5)	(173.0)	(239.4)	(297.7)		(521.1)		(363.0)
Comprehensive loss		$ (57.2)	$ (68.7)	$ (96.8)	$ (81.2)	$ (178.0)	$ (246.7)	$ (303.9)		$ (526.3)		$ (358.0)
Weighted-average common shares outstanding: basic (both Class A and B) (in shares) | shares		14.1	14.1	14.1	14.0	14.0	14.0	14.1	[1]	13.8	[1]	4.2	[1]
Weighted-average common shares outstanding: diluted (both Class A and B) (in shares) | shares		14.1	14.1	14.1	14.0	14.0	14.0	14.1	[1]	13.8	[1]	4.2	[1]
Loss per common share: basic (both Class A and B) (in dollars per share) | $ / shares		$ (4.13)	$ (4.71)	$ (6.77)	$ (5.54)	$ (12.36)	$ (17.10)	$ (21.11)	[1]	$ (37.76)	[1]	$ (86.43)	[1]
Loss per common share: diluted (both Class A and B) (in dollars per share) | $ / shares		$ (4.13)	$ (4.71)	$ (6.77)	$ (5.54)	$ (12.36)	$ (17.10)	$ (21.11)	[1]	$ (37.76)	[1]	$ (86.43)	[1]
Conversion ratio	0.0556
As reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Sales and marketing			$ 5.7	$ 25.4	$ 14.7	$ 40.1	$ 45.8
General and administrative			26.4	29.9	30.0	59.9	86.3
Total operating expenses			128.4	161.1	156.3	317.4	445.8
Operating loss			(54.7)	(80.7)	(70.9)	(151.6)	(206.3)
Loss before income taxes			(64.0)	(89.9)	(76.4)	(166.3)	(230.3)
Net loss			(64.0)	(89.9)	(76.4)	(166.3)	(230.3)
Comprehensive loss			$ (66.3)	$ (91.2)	$ (80.1)	$ (171.3)	$ (237.6)
Weighted-average common shares outstanding: basic (both Class A and B) (in shares) | shares			14.1	14.1	14.0	14.0	14.0
Weighted-average common shares outstanding: diluted (both Class A and B) (in shares) | shares			14.1	14.1	14.0	14.0	14.0
Loss per common share: basic (both Class A and B) (in dollars per share) | $ / shares			$ (4.54)	$ (6.38)	$ (5.46)	$ (11.88)	$ (16.45)
Loss per common share: diluted (both Class A and B) (in dollars per share) | $ / shares			$ (4.54)	$ (6.38)	$ (5.46)	$ (11.88)	$ (16.45)
Adjustments
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Sales and marketing			$ 2.4	$ (4.0)	$ 0.6	$ (3.4)	$ (1.0)
General and administrative			0.0	9.6	0.5	10.1	10.1
Total operating expenses			2.4	5.6	1.1	6.7	9.1
Operating loss			(2.4)	(5.6)	(1.1)	(6.7)	(9.1)
Loss before income taxes			(2.4)	(5.6)	(1.1)	(6.7)	(9.1)
Net loss			(2.4)	(5.6)	(1.1)	(6.7)	(9.1)
Comprehensive loss			$ (2.4)	$ (5.6)	$ (1.1)	$ (6.7)	$ (9.1)
Weighted-average common shares outstanding: basic (both Class A and B) (in shares) | shares
Weighted-average common shares outstanding: diluted (both Class A and B) (in shares) | shares
Loss per common share: basic (both Class A and B) (in dollars per share) | $ / shares
Loss per common share: diluted (both Class A and B) (in dollars per share) | $ / shares

[1] Reflects the 1-for-18 reverse stock split that became effective August 12, 2022. Refer to Note 2, “Basis of Presentation and Summary of Significant Accounting Policies.”