Significant Accounting Policies - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019	Sep. 30, 2018	Dec. 31, 2016	Dec. 31, 2013
Significant Accounting Policies [Line Items]
Contract liabilities	$ 800,000
Deferred tax assets	105,189,000	$ 77,061,000
Deferred tax asset, valuation allowance	104,298,000	75,436,000	$ 58,748,000			$ 59,806,000
Derecognition of build-to-suit asset and improvements							$ (22,300,000)
Operating lease costs	8,246,000
Depreciation expense	5,950,000,000	5,201,000,000	4,073,000,000
Interest expense	2,986,000	11,295,000	6,462,000
Operating lease right-of-use assets	22,160,000
Operating lease liabilities	25,277,000
Deferred rent obligations and lease incentives		1,700,000
Finance lease right-of-use assets	400,000
Finance lease liabilities	700,000
Cash and cash equivalents	420,712,000	437,892,000	188,986,000
Funds receivable	54,896,000	58,697,000
Goodwill impairment charges	$ 0	0
Accounts payable, unremitted ticket sale proceeds, net of fees and taxes	5 days
Advertising expense	$ 4,600,000	1,600,000	1,900,000
Deferred offering costs					$ 5,500,000
Foreign currency remeasurement gain (loss)	1,100,000	(7,400,000)	$ 3,100,000
San Francisco Office Lease
Significant Accounting Policies [Line Items]
Operating lease right-of-use assets	5,953,000
Tickets Sold on Behalf of Creators
Significant Accounting Policies [Line Items]
Funds receivable	51,100,000	54,800,000
Creator Cash
Significant Accounting Policies [Line Items]
Cash and cash equivalents	257,300,000	$ 217,400,000
ASU 2014-09
Significant Accounting Policies [Line Items]
Cumulative-effect adjustment to opening accumulated deficit				$ (600,000)
ASU 2014-09 | Accumulated Deficit
Significant Accounting Policies [Line Items]
Cumulative-effect adjustment to opening accumulated deficit				(600,000)
ASU 2016-02
Significant Accounting Policies [Line Items]
Cumulative-effect adjustment to opening accumulated deficit				(771,000)
Derecognition of build-to-suit asset and improvements				26,700,000
Derecognition of lease financing obligation				28,900,000
Operating lease right-of-use assets				25,700,000
Operating lease liabilities				29,700,000
Finance lease right-of-use assets				400,000
Finance lease liabilities				500,000
Deferred tax liability related to right-of-use asset				2,500,000
Deferred tax liability related to lease asset				3,000,000.0
ASU 2016-02 | San Francisco Office Lease
Significant Accounting Policies [Line Items]
Operating lease costs	3,700,000
Depreciation expense	(500,000)
Interest expense	$ (3,300,000)
Operating lease right-of-use assets				10,130,000
ASU 2016-02 | Accumulated Deficit
Significant Accounting Policies [Line Items]
Cumulative-effect adjustment to opening accumulated deficit				$ (771,000)