Goodwill and Intangible Assets - Narrative (Details)	3 Months Ended	9 Months Ended	12 Months Ended
	Jun. 30, 2021 USD ($)	Sep. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Goodwill [Line Items]
Goodwill		$ 134,759,000	$ 156,582,000	$ 199,238,000
Impairment charge		21,786,000	42,713,000
Accumulated impairment loss		$ 84,500,000	62,700,000
Royalty rate		0.040
Discount rate		0.145
Impairment charges, finite-lived		$ 0	0
Amortization of intangible assets		3,900,000	7,300,000
Brands and trademarks
Goodwill [Line Items]
Impairment charges, finite-lived		$ 0	$ 2,573,000
Zoosk, Inc.
Goodwill [Line Items]
Goodwill	$ 24,500,000
Impairment charge	21,800,000
Zoosk, Inc. | Brands and trademarks
Goodwill [Line Items]
Impairment charges, indefinite-lived	$ 10,300,000