1. Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash and cash equivalents:
Cash deposits	$ 12,730	$ 10,724
Money market funds	17,406	9,298
Total cash and cash equivalents	30,136	20,022	$ 28,346	$ 20,775
Short-term investments:
Mutual funds (trading)	222	0
Commercial paper (held-to-maturity)	31,220	0
Certificates of deposit (held-to-maturity)	4,020	24,000
Corporate bonds (held-to-maturity)	6	80
Total short-term investments	35,468	24,080
Long-term investments:
Corporate bonds (held-to-maturity)	5,000	5,000
Equity securities (available for sale)	4,136	4,945
Total long term investments	9,136	9,945
Total cash, cash equivalents and short and long-term investments	$ 74,740	$ 54,047