Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities
Net loss	$ (68,760,000)	$ (64,078,000)	$ (38,547,000)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	24,324,000	34,608,000	19,418,000
Amortization of creator signing fees	10,858,000	7,086,000	4,314,000
Noncash operating lease expense	8,246,000
Accretion of term loan	326,000	1,718,000	752,000
Loss on debt extinguishment	1,742,000	178,000	0
Change in fair value of redeemable convertible preferred stock warrant liability	0	9,591,000	2,200,000
Change in fair value of term loan embedded derivatives	0	(2,119,000)	0
Stock-based compensation	37,594,000	30,231,000	10,858,000
Impairment charges	5,671,000	3,425,000	2,715,000
Provision for bad debt and creator advances	2,433,000	2,742,000	921,000
Loss on disposal of equipment	73,000	99,000	1,271,000
Deferred income taxes	(380,000)	103,000	(400,000)
Excess tax benefit from stock-based compensation awards	0	0	(2,258,000)
Changes in operating assets and liabilities, net of impact of acquisitions:
Accounts receivable	(288,000)	(2,092,000)	(775,000)
Funds receivable	3,801,000	(6,810,000)	(18,148,000)
Creator signing fees, net	(21,216,000)	(15,973,000)	(8,600,000)
Creator advances, net	(5,685,000)	(5,308,000)	(5,782,000)
Prepaid expenses and other current assets	1,690,000	(5,594,000)	(4,347,000)
Other assets	201,000	(1,643,000)	668,000
Accounts payable, creators	36,170,000	24,523,000	52,836,000
Accounts payable, trade	670,000	(507,000)	386,000
Accrued compensation and benefits	761,000	1,791,000	(333,000)
Accrued taxes	(2,619,000)	5,039,000	3,640,000
Operating lease liabilities	(9,146,000)
Other accrued liabilities	2,224,000	4,256,000	693,000
Accrued taxes, noncurrent	(137,000)	(14,458,000)	7,027,000
Other liabilities	105,000	354,000	1,312,000
Net cash provided by operating activities	28,658,000	7,162,000	29,821,000
Cash flows from investing activities
Purchases of property and equipment	(5,888,000)	(5,418,000)	(2,536,000)
Capitalized internal-use software development costs	(7,710,000)	(7,232,000)	(6,142,000)
Acquisitions, net of cash acquired	0	12,611,000	(131,974,000)
Net cash used in investing activities	(13,598,000)	(39,000)	(140,652,000)
Cash flows from financing activities
Proceeds from initial public offering, net of underwriters' discounts and offering costs, net of reimbursements	0	240,965,000	0
Proceeds from issuance of common stock under ESPP	3,631,000	0	0
Proceeds from exercise of stock options	40,669,000	8,108,000	1,767,000
Excess tax benefit from stock-based compensation awards	0	0	2,258,000
Taxes paid related to net share settlement of equity awards	(1,066,000)	(9,013,000)	0
Proceeds from issuance of redeemable convertible preferred stock, net	0	0	133,936,000
Proceeds from term loans	0	118,578,000	30,000,000
Principal payments on debt obligations	(73,594,000)	(111,071,000)	(7,788,000)
Prepayment penalties on debt extinguishment	0	(6,803,000)	0
Payment of debt issuance costs	(457,000)	0	0
Payments on finance lease obligations	(290,000)
Payments on finance lease obligations		(78,000)	(249,000)
Payments on build-to-suit lease financing obligation	0	(630,000)	(410,000)
Payments of deferred offering costs	(413,000)	0	0
Net cash provided by (used in) financing activities	(31,520,000)	240,056,000	159,514,000
Net increase (decrease) in cash, cash equivalents and restricted cash	(16,460,000)	247,179,000	48,683,000
Net increase (decrease) in cash, cash equivalents and restricted cash
Beginning of period	439,400,000	192,221,000	143,538,000
End of period	422,940,000	439,400,000	192,221,000
Supplemental cash flow data
Interest paid	10,657,000	7,588,000	868,000
Income taxes paid, net of refunds	1,096,000	202,000	144,000
Noncash investing and financing activities
Vesting of early exercised stock options	367,000	366,000	366,000
Issued shares of common stock for acquisitions	0	8,832,000	18,243,000
Promissory notes issued in connection with acquisitions	0	0	57,500,000
Conversion of redeemable convertible preferred stock in connection with initial public offering	0	21,465,000	0
Issuance of redeemable convertible preferred stock warrants in connection with the loan facilities and term loan	0	4,603,000	5,071,000
Deferred offering costs included in accounts payable, trade and other accrued liabilities	0	430,000	0
Purchases of property and equipment, accrued but unpaid	436,000	$ 0	$ 0
Operating lease right-of-use assets obtained in exchange for operating lease liabilities	$ 3,704,000