Acquisitions - 2017 Acquisitions, Narrative (Details) - USD ($) $ in Thousands, shares in Millions	1 Months Ended				12 Months Ended
	Apr. 30, 2018	Mar. 31, 2018	Sep. 30, 2017	Jan. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Consideration transferred	$ 11,400
Repayment of long-term debt					$ 73,594	$ 111,071	$ 7,788
Loss on debt extinguishment					(1,742)	(178)	0
Net loss					$ 68,760	$ 64,078	38,547
Convertible Notes Payable | Promissory Note
Business Acquisition [Line Items]
Term of debt instrument			5 years
Annual interest rate			6.50%
Aggregate principal amount		$ 50,000
Repayment of long-term debt		34,700
Repayments of principal		33,000
Payments of interest		1,700
Loss on debt extinguishment		$ 17,000
TSTM Group Limited
Business Acquisition [Line Items]
Percentage of interests acquired				100.00%
Consideration transferred				$ 33,400
Payments to acquire businesses				7,700
Consideration transferred liabilities incurred				$ 7,500
Shares issued as consideration (in shares)				2.7
Number of options issued as consideration (in shares)				0.3
Acquisition costs				$ 1,200
Ticketfly, LLC
Business Acquisition [Line Items]
Percentage of interests acquired			100.00%
Consideration transferred			$ 201,100
Payments to acquire businesses			151,100
Consideration transferred liabilities incurred			$ 50,000
Acquisition costs							$ 500