CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash Flows Operating Activities:
Net loss	$ (191,995)	$ (57,294)	$ (31,125)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	13,294	11,169	6,260
Amortization of deferred contract acquisition costs	12,844	7,681	4,038
Stock-based compensation	173,443	43,280	273
Premium (discount) amortization on marketable securities	1,757	1,227	(194)
Gain realized on sale of marketable securities and non-marketable equity investments	(23,836)	(132)	(316)
Change in fair value of equity securities	(132)	(107)	(266)
Deferred income taxes	(1,907)	(2,360)	(939)
Other	(28)	143	386
Changes in operating assets and liabilities:
Accounts receivable	(17,509)	(9,932)	(9,366)
Deferred contract acquisition costs	(24,218)	(14,344)	(9,579)
Prepaid expenses and other assets	(5,942)	(8,165)	(11,340)
Accounts payable	1,986	53	2,665
Accrued and other liabilities	17,714	24,867	13,902
Deferred revenue	55,989	36,444	27,437
Net cash provided by (used in) operating activities	11,460	32,530	(8,164)
Cash Flows from Investing Activities:
Purchases of property and equipment	(5,565)	(4,383)	(11,505)
Proceeds from sale of property and equipment	620	0	0
Capitalized internal-use software	(3,552)	(4,631)	(3,323)
Sale of non-marketable equity investment	23,979	0	0
Purchases of marketable securities	(686,078)	(115,689)	(176,575)
Sales of marketable securities	131,170	18,658	24,707
Maturities and redemptions of marketable securities	119,130	101,445	23,719
Acquired intangible assets	0	(1,750)	0
Business combination, net of cash acquired	0	(5,075)	(5,972)
Net cash used in investing activities	(420,296)	(11,425)	(148,949)
Net Cash Provided by (Used in) Financing Activities [Abstract]
Proceeds from initial public offering, net of underwriting discounts	1,069,348	0	0
Proceeds from issuance of Series H redeemable convertible preferred stock, net of issuance costs	0	0	149,820
Sale of redeemable convertible preferred stock	0	0	100,000
Repurchase of redeemable convertible preferred stock	0	0	(100,000)
Proceeds from exercise of stock options	94	246	689
Payment of deferred offering costs	(6,830)	0	0
Payment of withholding taxes on net share settlement of equity awards	(3,343)	0	0
Payment of acquisition-related liabilities	(900)	(2,155)	(277)
Net cash provided by (used in) financing activities	1,058,369	(1,909)	150,232
Net increase (decrease) in cash, cash equivalents and restricted cash	649,533	19,196	(6,881)
Cash, cash equivalents and restricted cash, beginning of period	98,331	79,135	86,016
Cash, cash equivalents and restricted cash, end of period	747,864	98,331	79,135
Reconciliation of cash, cash equivalents and restricted cash to consolidated balance sheets:
Cash and cash equivalents	747,861	95,382	74,999
Restricted cash included in prepaid expenses and other current assets	0	1,930	3,114
Restricted cash included in other assets	3	1,019	1,022
Total cash, cash equivalents and restricted cash	747,864	98,331	79,135
Supplemental cash flow information:
Cash paid for taxes	10,458	5,075	3,461
Non-cash investing and financing activities:
Purchased property and equipment included in accrued expenses	492	62	1,393
Property and equipment acquired through tenant improvement allowance	0	322	1,524
Deferred purchase consideration for acquisition	0	900	2,883
Accretion of redeemable convertible preferred stock	2,646,662	1,560,524	553,339
Conversion of redeemable convertible preferred stock into common stock upon initial public offering	$ 5,541,758	$ 0	$ 0