CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash Flows From Operating Activities
Net loss	$ (260,309)	$ (119,370)	$ (105,828)
Adjustments to reconcile net loss to cash used in operating activities:
Depreciation and amortization expense	66,607	49,387	29,479
Non-cash operating lease costs	25,091	19,765	0
Amortization of deferred contract acquisition costs	29,267	17,324	10,821
Stock-based compensation expense	90,137	56,334	36,627
Amortization of debt discount and issuance costs	46,174	21,629	0
Net accretion of discounts and amortization of premiums on available-for-sale securities	8,357	1,642	(1,801)
Deferred income taxes	8,738	(6,145)	370
Provision for bad debt	3,804	3,368	2,488
Loss on extinguishment of debt	72,234	0	0
Exchange of convertible senior notes attributable to the accreted interest related to debt discount	(29,353)	0	0
Change in fair value of redeemable convertible preferred stock warrant liability	0	0	1,517
Other	511	1	304
Changes in operating assets and liabilities, net of effect of acquisitions:
Accounts receivable, net	(35,848)	(33,000)	(11,200)
Contract assets	(2,541)	(1,475)	(511)
Deferred contract acquisition costs	(55,411)	(36,315)	(20,065)
Prepaid expenses and other current assets	(2,395)	(11,634)	(7,621)
Other noncurrent assets	1,534	(2,268)	(1,575)
Accounts payable	2,462	1,690	(1,328)
Accrued expenses and other current liabilities	58,897	17,075	12,334
Operating lease liabilities	(23,071)	(20,718)	0
Deferred revenue	64,390	25,189	14,610
Other noncurrent liabilities	(4,627)	392	2,462
Net cash provided by (used in) operating activities	64,648	(17,129)	(38,917)
Cash Flows From Investing Activities
Purchases of property and equipment	(92,986)	(56,375)	(43,289)
Capitalized internal-use software	(14,752)	(18,587)	(13,990)
Cash paid for acquisitions, net of cash acquired	(5,605)	(13,941)	0
Purchases of available-for-sale securities	(1,589,265)	(1,267,015)	(537,382)
Sales of available-for-sale securities	25,714	0	1,978
Maturities of available-for-sale securities	967,519	840,248	174,998
Other investing activities	53	397	44
Net cash used in investing activities	(709,322)	(515,273)	(417,641)
Cash Flows From Financing Activities
Proceeds from initial public offering, net of underwriting discounts and commissions	0	0	570,544
Gross proceeds from issuance of convertible senior notes	1,293,750	575,000	0
Purchases of capped calls related to convertible senior notes	(86,293)	(67,333)	0
Cash consideration paid in exchange of convertible senior debt	(370,647)	0	0
Cash paid for issuance costs on convertible senior notes	(19,797)	(12,542)	0
Proceeds from the exercise of stock options	21,385	7,457	3,058
Proceeds from the early exercise of stock options	115	241	2,909
Repurchases of unvested common stock	(189)	(157)	(283)
Payments on note payable	0	(200)	(255)
Proceeds from the issuance of common stock for employee stock purchase plan	14,984	10,923	0
Proceeds from build-to-suit lease financing obligation drawdown			63
Payments of deferred offering costs	0	0	(5,268)
Payment of indemnity holdback	(2,188)	0	0
Net cash provided by financing activities	847,486	504,912	570,768
Net increase in cash, cash equivalents, and restricted cash	202,812	(27,490)	114,210
Cash, cash equivalents, and restricted cash, beginning of period	118,146	145,636	31,426
Cash, cash equivalents, and restricted cash, end of period	320,958	118,146	145,636
Supplemental Disclosure of Cash Flow Information:
Cash paid for interest	3,634	2,192	786
Cash paid for income taxes, net of refunds	1,546	702	1,042
Cash paid for operating lease liabilities	22,765	20,895	0
Supplemental Disclosure of Non-cash Investing and Financing Activities:
Stock-based compensation capitalized for software development	3,212	3,423	1,975
Accounts payable and accrued expenses related to property and equipment additions	13,544	3,052	3,571
Vesting of early exercised stock options	3,878	4,744	3,668
Deferred offering costs, accrued but not paid	0	0	236
Indemnity holdback consideration associated with business combinations	0	2,187	0
Issuance of common stock related to an acquisition	1,565	1,821	0
Operating lease right-of-use assets obtained in exchange for operating lease liabilities	109,821	9,893	0
Derecognition of build-to-suit lease	0	9,886	0
Conversion of redeemable convertible preferred stock to common stock	0	0	331,521
Conversion of redeemable convertible preferred stock warrant liability reclassified to additional paid-in capital	0	0	3,135
Issuance of common stock for exchange of convertible senior notes	920,249	0	0
Outstanding and unsettled restricted stock units (RSUs)
Cash Flows From Financing Activities
Payment of tax withholding obligation	(3,634)	(8,101)	0
Shares issuable pursuant to the ESPP
Cash Flows From Financing Activities
Payment of tax withholding obligation	$ 0	$ (376)	$ 0