Investments - Cost vs FV (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Gross Amortized Cost
Due in one year or less	$ 57,758	$ 58,213
Total	57,758	58,213
Fair Value
Due in one year or less	57,757	58,217
Total	$ 57,757	$ 58,217