Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating Activities
Net loss	$ (601.5)	$ (494.1)	$ (270.2)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	86.3	64.4	51.2
Stock-based compensation	234.5	386.3	43.2
Equity in loss of unconsolidated entity	12.2	1.3	0.0
Change in acquisition related contingent consideration	(2.2)	(4.7)	8.9
Bad debt expense	7.3	8.9	16.0
Amortization of debt issuance costs	0.9	1.1	0.3
Changes in operating assets and liabilities:
Accounts receivable	6.5	8.5	(16.3)
Compass Concierge receivables	(11.7)	9.4	16.6
Other current assets	17.6	(40.0)	19.4
Other non-current assets	9.8	(11.8)	(4.9)
Operating lease right-of-use assets and operating lease liabilities	5.8	2.4	34.6
Accounts payable	(4.8)	(3.3)	(6.5)
Commissions payable	(15.9)	(0.3)	29.1
Accrued expenses and other liabilities	(36.5)	43.3	20.5
Net cash used in operating activities	(291.7)	(28.6)	(58.1)
Investing Activities
Proceeds from sales and maturities of marketable securities	0.0	0.0	55.5
Investment in unconsolidated entity	(15.0)	(5.0)	0.0
Capital expenditures	(70.1)	(50.1)	(43.3)
Payments for acquisitions, net of cash acquired	(15.0)	(137.4)	(25.6)
Net cash used in investing activities	(100.1)	(192.5)	(13.4)
Financing Activities
Proceeds from exercise and early exercise of stock options	9.0	26.9	15.9
Proceeds from issuance of common stock under the Employee Stock Purchase Plan	2.3	0.0	0.0
Taxes paid related to net share settlement of equity awards	(23.5)	(62.4)	0.0
Payments related to acquisitions, including contingent consideration	(17.5)	(10.7)	(3.2)
Proceeds from issuance of common stock upon initial public offering, net of offering costs	0.0	439.6	0.0
Other	(0.6)	(1.9)	(1.2)
Net cash provided by financing activities	135.4	399.3	19.9
Net (decrease) increase in cash and cash equivalents	(256.4)	178.2	(51.6)
Cash and cash equivalents at beginning of period	618.3	440.1	491.7
Cash and cash equivalents at end of period	361.9	618.3	440.1
Supplemental disclosures of cash flow information:
Cash paid for interest	2.3	1.3	0.2
Supplemental non-cash information:
Issuance of common stock for acquisitions	3.6	10.1	1.2
Conversion of convertible preferred stock in connection with initial public offering	0.0	1,419.1	0.0
Concierge credit facility
Financing Activities
Proceeds from drawdowns on Concierge credit facility	59.0	39.5	11.4
Repayments of drawdowns on Concierge credit facility	(43.3)	(31.7)	(3.0)
Revolving credit facility
Financing Activities
Proceeds from drawdowns on Concierge credit facility	150.0	0.0	0.0
Series D
Supplemental non-cash information:
Conversion of stock, amount issued	$ 0.0	$ 67.6	$ 40.0