Goodwill and Intangible Assets - Narrative (Details)	5 Months Ended	12 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2019 USD ($) unit segment	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Aug. 15, 2019 USD ($)
Finite-Lived Intangible Assets [Line Items]
Number of operating segments | segment		2
Number of reportable segments | segment		1
Number of reporting units | unit		2
Goodwill impairment		$ 0	$ 0	$ 0
Amortization expense of intangible assets		9,600,000	4,300,000	3,400,000
Impairment of intangible assets		$ 0	$ 0	$ 0
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Intangible asset, useful life		15 years
Trademark
Finite-Lived Intangible Assets [Line Items]
Intangible asset, useful life		15 years
Referral agreement
Finite-Lived Intangible Assets [Line Items]
Intangible asset, useful life		10 years
Reverb Holdings Inc.
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangibles					$ 172,900,000
Reverb Holdings Inc. | Customer relationships
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangibles	$ 93,500,000	$ 93,500,000			93,500,000
Acquired intangible asset, useful life	15 years
Reverb Holdings Inc. | Trademark
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangibles	$ 79,400,000	$ 79,400,000			$ 79,400,000
Acquired intangible asset, useful life	15 years