CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash Flows Operating Activities:
Net loss	$ (117,259)	$ (55,759)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	9,792	8,215
Amortization of deferred contract acquisition costs	9,085	5,374
Stock-based compensation	124,259	43,280
Premium amortization on marketable securities	1,206	874
Gain realized on sale of marketable securities and non-marketable equity investment	(23,835)	(132)
Change in fair value of equity securities	(100)	(44)
Deferred income taxes	(11,721)	0
Other	133	184
Changes in operating assets and liabilities:
Accounts receivable	(10,039)	(6,116)
Deferred contract acquisition costs	(17,032)	(9,935)
Prepaid expenses and other assets	(14,823)	(6,312)
Accounts payable	(542)	(2,529)
Accrued and other liabilities	18,517	17,267
Deferred revenue	38,975	24,682
Net cash provided by operating activities	6,616	19,049
Cash Flows from Investing Activities:
Purchases of property and equipment	(4,056)	(3,628)
Proceeds from sale of property and equipment	565	0
Capitalized internal-use software	(3,050)	(3,828)
Sale of non-marketable equity investment	23,979	0
Purchases of marketable securities	(154,828)	(99,058)
Sales of marketable securities	36,831	15,658
Maturities and redemptions of marketable securities	112,554	59,462
Acquired intangible assets	0	(1,750)
Business combination, net of cash acquired	0	(5,075)
Net cash provided by (used in) investing activities	11,995	(38,219)
Cash Flows from Financing Activities:
Proceeds from initial public offering, net of underwriting discounts	1,069,348	0
Proceeds from exercise of stock options	43	121
Payment of deferred offering costs	(5,472)	0
Payment of acquisition-related liabilities	(900)	(1,200)
Net cash provided by (used in) financing activities	1,063,019	(1,079)
Net increase (decrease) in cash, cash equivalents and restricted cash	1,081,630	(20,249)
Cash, cash equivalents and restricted cash, beginning of period	98,331	79,135
Cash, cash equivalents and restricted cash, end of period	1,179,961	58,886
Reconciliation of cash, cash equivalents and restricted cash to consolidated balance sheets:
Cash and cash equivalents	1,179,958	55,951
Restricted cash included in prepaid expenses and other current assets	0	1,916
Restricted cash included in other assets	3	1,019
Total cash, cash equivalents and restricted cash	1,179,961	58,886
Supplemental cash flow information:
Cash paid for taxes	6,981	3,273
Non-cash investing and financing activities:
Purchased property and equipment included in accrued expenses	16	187
Property and equipment acquired through tenant improvement allowance	0	322
Deferred offering costs	1,423	0
Deferred purchase consideration for acquisition	0	900
Accretion of redeemable convertible preferred stock	$ 2,646,662	$ 371,522