Acquisitions, Investments and Licenses - Summary of Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Business Combinations [Abstract]
Equity method investments	$ 21,753
Variable interest entity, equity method	545
Equity securities	12,879
Equity securities with no readily determinable fair value	1,108
Warrants and options	5,004
Total carrying value of investments	41,289	$ 40,642
Equity method investment, underlying equity in net assets	$ 23,590