4. Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Certificates of Deposits [Member] | Short Term Investments [Member]
Schedule of Held-to-maturity Securities [Line Items]
Cost	$ 18,107	$ 24,000
Gross Unrealized Gains	1	9
Gross Unrealized Losses	(2)	0
Fair Value	18,106	24,009
Commercial Paper [Member] | Short Term Investments [Member]
Schedule of Held-to-maturity Securities [Line Items]
Cost	8,960
Gross Unrealized Gains	0
Gross Unrealized Losses	(4)
Fair Value	8,956
Corporate Bond Securities [Member] | Short Term Investments [Member]
Schedule of Held-to-maturity Securities [Line Items]
Cost	6	80
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	6	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	(63)	(287)
Fair Value	4,937	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	(629)	(730)
Fair Value	$ 5,046	$ 4,945