Investments - Accounting Method, Carrying Value and Underlying Equity in Net Assets of Unconsolidated Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Long-term Investments [Abstract]
Equity method investments, carrying value	$ 826
Variable interest entity, equity method, carrying value	894
Available for sale investments, carrying value	18,870
Cost method investment	36
Warrants and options	120
Total carrying value of investments	20,746	$ 31,228
Equity method Investments, underlying equity in net assets	9,931
Variable interest entity, equity method, underlying equity in net assets	$ 0