Investments - Components of Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Strategic investments:
Investments accounted for under the equity method	$ 17,313	$ 16,707
Investments held at fair value	2,379	9,198
Investments held at cost, less impairment	2,790	2,789
Total strategic investments	22,482	28,694
Other investments	2,234	2,285
Total investments	$ 24,716	$ 30,979