Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash Flows From Operating Activities:
Net loss	$ (222,962)	$ (184,780)	$ (163,929)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	10,741	3,853	3,534
Share-based compensation expense	180,739	160,743	142,660
Non-cash operating leases expense	2,527	2,281	2,115
Non-cash postcombination compensation expense	32,430	0	0
Amortization of premium on short-term investments	(4,495)	277	1,162
Gain on sale of equity method investment	0	(17,889)	0
Impairment of other financial instruments	0	11,616	0
Other	736	649	3,110
Changes in operating assets and liabilities:
Accounts receivable	(4,556)	(2,577)	(4,940)
Settlements receivable	(11,894)	(6,762)	1,601
Network incentives receivable	(11,146)	(12,262)	(10,377)
Prepaid expenses and other assets	7,900	(8,621)	(7,742)
Accounts payable	(1,956)	254	190
Revenue share payable	31,451	21,015	42,988
Accrued expenses and other liabilities	14,983	22,257	49,372
Operating lease liabilities	(3,394)	(3,020)	(2,772)
Net cash provided by (used in) operating activities	21,104	(12,966)	56,972
Cash flows from investing activities:
Purchases of property and equipment	(762)	(2,319)	(2,743)
Capitalization of internal-use software	(11,889)	0	0
Business combination, net of cash acquired	(135,777)	0	0
Purchase of patents	0	(1,600)	0
Purchases of short-term investments	(892,430)	(70,495)	(455,266)
Sales of short-term investments	577,934	0	0
Maturities of short-term investments	501,534	77,400	148,888
Realized gain/loss on investments	(94)	0	0
Purchase of equity method investment and purchase option	0	0	(20,000)
Sale of equity method investment	0	25,732	0
Net cash provided by (used in) investing activities	38,516	28,718	(329,121)
Cash flows from financing activities:
Proceeds from initial public offering, net of underwriters’ discounts and commissions	0	0	1,319,809
Proceeds from exercise of stock options, including early exercised stock options, net of repurchase of early exercised unvested options	5,289	9,249	4,539
Payment of contingent consideration	(53,067)	0
Proceeds from exercise of warrants	0	0	60
Proceeds from shares issued in connection with employee stock purchase plan	3,066	4,762	3,201
Taxes paid related to net share settlement of restricted stock units	(26,662)	(15,362)	(23,552)
Repurchase of common stock	(190,420)	(78,136)	0
Payment of deferred offering costs	0	0	(4,760)
Net cash (used in) provided by financing activities	(261,794)	(79,487)	1,299,297
(Decrease) Increase in cash, cash equivalents, and restricted cash	(202,174)	(63,735)	1,027,148
Cash, cash equivalents, and restricted cash - Beginning of period	1,191,646	1,255,381	228,233
Cash, cash equivalents, and restricted cash - End of period	989,472	1,191,646	1,255,381
Reconciliation of cash, cash equivalents, and restricted cash
Cash and cash equivalents	980,972	1,183,846	1,247,581
Restricted cash	8,500	7,800	7,800
Total cash, cash equivalents, and restricted cash	989,472	1,191,646	1,255,381
Supplemental disclosures of cash flow information:
Cash paid for operating lease liabilities	4,239	4,112	4,081
Cash paid for interest	0	0	0
Cash paid for income taxes	430	84	201
Supplemental disclosures of non-cash investing and financing activities:
Purchase of property and equipment accrued and not yet paid	113	563	1,190
Share-based compensation capitalized to internal-use software	4,492	0	0
Repurchase of common stock accrued and not yet paid	991	1,065	0
Vesting of early exercised stock options	$ 0	$ 298	$ 0