Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Finite Lived Intangible Assets [Line Items]
Weighted-average amortization period	58 months	61 months
Accumulated Amortization	$ (34,664)	$ (27,182)
Net Carrying Amount	31,067
Indefinite-lived trade name	3,600	3,600
Foreign currency translation adjustment	(398)	(271)
Total intangible assets, gross carrying amount	69,331	53,097
Intangible assets, net	$ 34,667	$ 25,915
Developed technologies and content library
Finite Lived Intangible Assets [Line Items]
Weighted-average amortization period	66 months	71 months
Gross Carrying Amount	$ 43,268	$ 31,667
Accumulated Amortization	(18,395)	(13,737)
Net Carrying Amount	$ 24,873	$ 17,930
Customer lists
Finite Lived Intangible Assets [Line Items]
Weighted-average amortization period	47 months	47 months
Gross Carrying Amount	$ 9,970	$ 9,970
Accumulated Amortization	(8,210)	(6,847)
Net Carrying Amount	$ 1,760	$ 3,123
Trade and domain names
Finite Lived Intangible Assets [Line Items]
Weighted-average amortization period	46 months	44 months
Gross Carrying Amount	$ 10,873	$ 6,113
Accumulated Amortization	(6,169)	(4,863)
Net Carrying Amount	$ 4,704	$ 1,250
Non-compete agreements
Finite Lived Intangible Assets [Line Items]
Weighted-average amortization period	31 months	31 months
Gross Carrying Amount	$ 2,018	$ 2,018
Accumulated Amortization	(1,890)	(1,735)
Net Carrying Amount	128	$ 283
Internships Dot Com
Finite Lived Intangible Assets [Line Items]
Indefinite-lived trade name	$ 3,600