4. Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Certificates of Deposits [Member] | Short Term Investments [Member]
Schedule of Held-to-maturity Securities [Line Items]
Cost	$ 18,063	$ 24,000
Gross Unrealized Gains	2	9
Gross Unrealized Losses	(2)	0
Fair Value	18,063	24,009
Commercial Paper [Member] | Short Term Investments [Member]
Schedule of Held-to-maturity Securities [Line Items]
Cost	10,926
Gross Unrealized Gains	24
Gross Unrealized Losses	(7)
Fair Value	10,943
Corporate Bond Securities [Member] | Short Term Investments [Member]
Schedule of Held-to-maturity Securities [Line Items]
Cost	30	80
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	30	80
Corporate Bond Securities [Member] | Long Term Investments [Member]
Schedule of Held-to-maturity Securities [Line Items]
Cost	5,000	5,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(191)	(287)
Fair Value	4,809	4,713
Equity Investments [Member] | Long Term Investments [Member]
Schedule of Held-to-maturity Securities [Line Items]
Cost	5,675	5,675
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(1,212)	(730)
Fair Value	$ 4,463	$ 4,945