2. Investments (Tables)

12 Months Ended

Dec. 31, 2017

Investments Schedule [Abstract]

Investments, Held-to-Maturity Securities

					Gross Unrealized
	Level		Cost		Gains		Losses			Fair value
As of December 31, 2017:
Short-term Investments:
Certificates of deposit		2	$	4,020	$	--	$	(3	)	$	4,017
Commercial paper		2	$	31,220	$	26	$	(38	)	$	31,208
Corporate bonds		2	$	6	$	--	$	--		$	6
Mutual funds		1	$	219	$	3	$	--		$	222
Long-term Investments:
Corporate bonds		2	$	5,000	$	--	$	(75	)	$	4,925
Equity investments		2	$	5,675	$	--	$	(1,539	)	$	4,136
As of December 31, 2016:
Short-term Investments:
Certificates of deposit		2	$	24,000	$	9	$	--		$	24,009
Corporate bonds		2	$	80	$	--	$	--		$	80
Long-term Investments:
Corporate bonds		2	$	5,000	$	--	$	(287	)	$	4,713
Equity investments		2	$	5,675	$	--	$	(730	)	$	4,945