Investments (Details 1) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Proceeds from sales of marketable securities	$ 500,000	$ 107,000
Fair Value
Due in less than 1 year	14,156,000		$ 11,839,000
Due in 1-5 years	29,467,000		0
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Fair Value	1,007,000		0
Total	44,630,000		11,839,000
Amortized Cost
Due in less than 1 year	14,149,000		11,851,000
Due in 1-5 years	29,435,000		0
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Amortized Cost Basis	1,005,000		0
Total	$ 44,589,000		$ 11,851,000