Fair Value - Narrative (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($) showroom	Mar. 31, 2021 USD ($) showroom	Dec. 09, 2020 USD ($)	Jun. 30, 2020 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Changes in inputs and valuation techniques | showroom			0
Investment owned, at cost			$ 2,000
Purchases of level 3 assets			0
Sales of level 3 assets			0
Impairment loss	$ 200	$ 2,200
Number of showrooms consolidated | showroom		4
Poppin, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Contingent earn-out liability			31,800	$ 31,800
Poppin, Inc. | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Contingent earn-out liability				$ 70,000
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Contingent earn-out liability			31,790
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Contingent earn-out liability			0
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Contingent earn-out liability			0
Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Equity securities not readily marketable			500
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Contingent earn-out liability			31,790
Warrant | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Derivative asset, fair value, gross asset			1,500		$ 1,500
Warrant | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Derivative asset, fair value, gross asset			0		0
Warrant | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Derivative asset, fair value, gross asset			0		0
Warrant | Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Derivative asset, fair value, gross asset			1,500		$ 1,500
Not Designated as Hedging Instrument | Other Assets | Warrant | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Derivative asset, fair value, gross asset			$ 1,500