Intangible Assets - Summary of Gross Carrying Amount and Accumulated Amortization for Intangible Assets Intangible Assets (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross	$ 142,819	$ 138,569
Accumulated Amortization	(90,142)	(68,817)
Net	$ 52,677	$ 69,752
Weighted Average Amortization Period (Years)	2 years 6 months	3 years
Media service rights
Finite-Lived Intangible Assets [Line Items]
Gross	$ 35,934	$ 34,684
Accumulated Amortization	(23,135)	(16,098)
Net	$ 12,799	$ 18,586
Weighted Average Amortization Period (Years)	1 year 8 months 12 days	2 years 2 months 12 days
Promotion service rights
Finite-Lived Intangible Assets [Line Items]
Gross	$ 33,548	$ 30,548
Accumulated Amortization	(15,072)	(10,682)
Net	$ 18,476	$ 19,866
Weighted Average Amortization Period (Years)	2 years 8 months 12 days	3 years 7 months 6 days
Developed technologies
Finite-Lived Intangible Assets [Line Items]
Gross	$ 27,170	$ 27,170
Accumulated Amortization	(17,344)	(12,790)
Net	$ 9,826	$ 14,380
Weighted Average Amortization Period (Years)	2 years 8 months 12 days	3 years 2 months 12 days
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross	$ 22,690	$ 22,690
Accumulated Amortization	(15,211)	(12,267)
Net	$ 7,479	$ 10,423
Weighted Average Amortization Period (Years)	2 years 9 months 18 days	3 years 3 months 18 days
Data access rights
Finite-Lived Intangible Assets [Line Items]
Gross	$ 10,801	$ 10,801
Accumulated Amortization	(7,825)	(6,415)
Net	$ 2,976	$ 4,386
Weighted Average Amortization Period (Years)	1 year 7 months 6 days	2 years 3 months 18 days
Domain names
Finite-Lived Intangible Assets [Line Items]
Gross	$ 5,948	$ 5,948
Accumulated Amortization	(5,590)	(5,540)
Net	$ 358	$ 408
Weighted Average Amortization Period (Years)	1 month 6 days	9 months 18 days
Trade names
Finite-Lived Intangible Assets [Line Items]
Gross	$ 2,823	$ 2,823
Accumulated Amortization	(2,135)	(1,560)
Net	$ 688	$ 1,263
Weighted Average Amortization Period (Years)	7 months 6 days	2 years 2 months 12 days
Vendor relationships
Finite-Lived Intangible Assets [Line Items]
Gross	$ 2,510	$ 2,510
Accumulated Amortization	(2,510)	(2,172)
Net	$ 0	$ 338
Weighted Average Amortization Period (Years)	0 years	4 months 24 days
Patents
Finite-Lived Intangible Assets [Line Items]
Gross	$ 975	$ 975
Accumulated Amortization	(900)	(873)
Net	$ 75	$ 102
Weighted Average Amortization Period (Years)	2 years 1 month 6 days	2 years 9 months 18 days
Registered users
Finite-Lived Intangible Assets [Line Items]
Gross	$ 420	$ 420
Accumulated Amortization	(420)	(420)
Net	$ 0	$ 0
Weighted Average Amortization Period (Years)	0 years	0 years