Business Combination - Schedule of Preliminary Allocation of Purchase Consideration to Tangible and Intangible Assets Acquired and Liabilities Assumed (Details) - USD ($)	Dec. 31, 2019	Nov. 08, 2019	Dec. 31, 2018
Assets acquired
Goodwill	$ 74,116,000		$ 1,382,000
Boston-based Dataxu, Inc, Demand-Side Platform (DSP)
Assets acquired
Current assets		$ 50,829,000
Restricted cash		1,303,000
Property and equipment, net		4,503,000
Intangible assets		70,200,000
Goodwill	$ 72,700	72,733,000
Operating lease right-of-use assets		24,658,000
Other long-term assets		235,000
Total assets acquired		224,461,000
Liabilities assumed
Current liabilities		(51,428,000)
Operating lease liabilities		(24,658,000)
Total liabilities assumed		(76,086,000)
Total preliminary purchase consideration		$ 148,375,000