Business Combinations - Narrative (Details) - USD ($) $ in Thousands		5 Months Ended	12 Months Ended
	Aug. 15, 2019	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Acquisition of businesses, net of cash acquired			$ 270,409	$ 0	$ 0
Revenue			818,379	603,693	441,231
Net loss			(95,894)	(77,491)	$ (81,800)
Reverb Holdings Inc.
Business Acquisition [Line Items]
Acquisition of businesses, net of cash acquired	$ 270,400
Revenue		$ 19,100
Net loss		$ 9,900
Acquisition-related expenses			3,900
Non-recurring acquisition-related expenses			88,595	53,587
Acquisition-related Costs | Reverb Holdings Inc.
Business Acquisition [Line Items]
Non-recurring acquisition-related expenses			$ 6,100	$ 2,000