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	$ (163,929)	$ (47,695)	$ (58,200)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	3,534	3,498	3,080
Share-based compensation expense	142,660	28,211	21,757
Non-cash operating leases expense	2,115	2,029	1,487
Amortization of premium (accretion of discount) on marketable securities	1,162	543	(499)
Provision for doubtful accounts	173	39	370
Other	2,937	1,890	1,000
Changes in operating assets and liabilities:
Accounts receivable	(4,940)	(4,485)	(2,812)
Settlements receivable	1,601	(2,961)	(4,000)
Network incentives receivable	(10,377)	(9,400)	(8,248)
Prepaid expenses and other assets	(7,742)	(2,481)	(5,363)
Accounts payable	190	(839)	1,613
Revenue share payable	42,988	48,442	18,631
Accrued expenses and other liabilities	49,372	34,997	17,407
Operating lease liabilities	(2,772)	(1,515)	(1,651)
Net cash provided by (used in) operating activities	56,972	50,273	(15,428)
Cash flows from investing activities:
Purchases of property and equipment	(2,743)	(2,375)	(4,908)
Purchases of marketable securities	(455,266)	(216,200)	(528,300)
Sales of marketable securities	0	71,981	0
Maturities of marketable securities	148,888	89,032	433,640
Purchase of equity method investment and purchase option	(20,000)	0	(750)
Net cash used in investing activities	(329,121)	(57,562)	(100,318)
Cash flows from financing activities:
Proceeds from initial public offering, net of underwriters’ discounts and commissions	1,319,809	0	0
Proceeds from issuance of redeemable convertible preferred stock, net of issuance costs	0	166,942	142,990
Payment of bank loan and related fees	0	0	(5,005)
Proceeds from exercise of stock options, including early exercised stock options, net of repurchase of early exercised unvested options	4,539	3,144	1,064
Proceeds from exercise of warrants	60	0	0
Proceeds from shares issued in connection with employee stock purchase plan	3,201	0	0
Taxes paid related to net share settlement of restricted stock units	23,552	0	0
Payment of deferred offering costs	(4,760)	(2,708)	0
Net cash provided by financing activities	1,299,297	167,378	139,049
Net increase in cash, cash equivalents, and restricted cash	1,027,148	160,089	23,303
Cash, cash equivalents, and restricted cash- Beginning of period	228,233	68,144	44,841
Cash, cash equivalents, and restricted cash - End of period	$ 1,255,381	$ 228,233	$ 68,144