Acquisitions - Acquired Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 277,263	$ 278,337	$ 251,024
Gameiom Technologies Limited [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill	3,700
Total intangible assets	$ 2,100
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	6 years 8 months