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	$ (135,618)	$ (55,320)	$ (51,951)
Adjustments to reconcile net loss to net cash provided by operating activities:
Stock-based compensation	98,482	54,307	36,086
Depreciation and amortization	36,526	20,233	15,807
Amortization of debt issuance costs	1,367
Asset impairments		794
Impairment of capitalized cloud computing costs	667
Deferred income tax expense (benefit)	1,128	(9,419)	(223)
Non-cash operating lease costs	9,549	8,111	5,000
Fair value changes in earnout liabilities	12,231	(2,325)	(1,043)
Non-cash bad debt expense	1,801	2,063	1,367
Other	(783)	(230)	104
Changes in operating assets and liabilities:
Trade accounts receivable	(36,053)	(17,921)	(12,862)
Prepaid expenses and other current assets	(10,986)	(3,333)	(3,544)
Deferred commissions	(17,648)	(12,454)	(19,149)
Other noncurrent assets	(4,362)	(2,843)	(1,265)
Trade payables	(4,240)	8,026	5,783
Accrued expenses	22,646	23,979	16,246
Deferred revenue	71,406	39,254	37,558
Operating lease liabilities	(11,995)	(10,304)	(5,764)
Net cash provided by operating activities	34,118	42,618	22,150
Cash flows from investing activities:
Purchase of property and equipment	(7,659)	(4,501)	(7,885)
Capitalized software development costs	(13,764)	(4,159)	(2,295)
Cash paid for acquisitions of businesses, net of cash and restricted cash equivalents acquired	(76,646)	(368,198)	(30,310)
Cash paid for acquired intangible assets	(1,900)	(1,200)	(139)
Cash paid for purchases of customer fund available-for-sale securities	(381)
Net cash used in investing activities	(100,350)	(378,058)	(40,629)
Cash flows from financing activities:
Proceeds from common stock offering, net of underwriting discounts		556,312	274,705
Payments of deferred financing costs		(686)	(555)
Proceeds from convertible senior notes	977,500
Payments of debt issuance costs	(17,609)
Purchase of capped calls	(75,268)
Proceeds from exercise of stock options	21,779	39,946	58,019
Proceeds from purchases of stock under employee stock purchase plan	14,446	11,337	12,293
Taxes paid related to net share settlement of stock-based awards			(1,183)
Acquisition-related post-closing payments	(20,821)	(2,763)
Payments related to business combination earnouts	(33)	(3,760)	(375)
Payments related to asset acquisition earnouts	(1,266)	(65)
Payments on financed asset purchases	(104)
Net increase in customer fund obligations	20,288	5,738	11,506
Net cash provided by financing activities	918,912	606,059	354,410
Foreign currency effect	(621)	(108)	(33)
Net change in cash, cash equivalents, restricted cash, and restricted cash equivalents	852,059	270,511	335,898
Cash, cash equivalents, restricted cash, and restricted cash equivalents—Beginning of period	761,844	491,333	155,435
Cash, cash equivalents, restricted cash, and restricted cash equivalents—End of period	1,613,903	761,844	491,333
Reconciliation of cash, cash equivalents, restricted cash, and restricted cash equivalents to the Consolidated Balance Sheets, end of period:
Cash and cash equivalents	1,514,064	673,593	466,950
Restricted cash	37,700	57,653
Restricted cash equivalents—funds held from customers	62,139	30,598	24,383
Supplemental cash flow disclosures:
Cash paid for interest expense	0	0	122
Cash paid for operating lease liabilities	15,563	14,492	9,784
Cash paid for income taxes	1,582	1,155	1,121
Non-cash investing and financing activities:
Stock issued related to business combinations	22,971	8,690	0
Accrued purchase price related to acquisitions	10,055	69,600	4,902
Accrued value of earnout related to acquisitions of businesses	67,280	34,468	15,351
Accrued purchase of intangible assets	1,197	716	147
Fair value of common stock issued to purchase intangible assets	0	87	98
Customer fund obligations assumed in business combinations	12,464	0	0
Property and equipment additions in accounts payable and accrued expenses	1,011	837	768
Capitalized internally developed software costs included in accounts payable and accrued expenses	1,449	0	0
Stock-based compensation costs capitalized to internally developed software	1,397	430	51
Operating lease right-of-use assets in exchange for lease obligations	$ 1,614	$ 11,835	$ 15,861