1. Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash and cash equivalents:
Cash deposits	$ 24,670	$ 12,730
Money market funds	30,965	17,406
Commercial paper	3,118	0
Total cash and cash equivalents	58,753	30,136	$ 20,022	$ 28,346
Short-term investments:
Mutual funds (trading)	0	222
Commercial paper (held-to-maturity)	1,275	31,220
Certificates of deposit (held-to-maturity)	0	4,020
Corporate bonds (held-to-maturity)	8,409	6
Total short-term investments	9,684	35,468
Long-term investments:
Mutual funds (available for sale)	674	0
Corporate bonds (held-to-maturity)	17,513	5,000
Equity securities (available for sale)	2,861	4,136
Total long term investments	21,048	9,136
Total cash, cash equivalents and short and long-term investments	$ 89,485	$ 74,740