Available-for-sale securities (Tables)

3 Months Ended

Mar. 31, 2016

Investments, Debt and Equity Securities [Abstract]

Investments Classified by Contractual Maturity Date [Table Text Block]

The contractual maturities of available-for-sale securities were as follows:

	March 31, 2016
(in thousands)	Less than 12 months		1-3 Years	Over 3 Years	Total
Certificates of deposit	$	750	—	254	1,004
Corporate bonds	1,004		4,883	999	6,886
Total	$	1,754	4,883	1,253	7,890

Available-for-sale Securities [Table Text Block]

The Company had no available-for-sale securities as of March 31, 2015.

	March 31, 2016
(in thousands)	Amortized Cost		Gains in Accumulated Other Comprehensive Loss	Losses in Accumulated Other Comprehensive Loss		Estimated Fair Value
Certificates of deposit	$	1,000	4	—		1,004
Corporate bonds	6,969		—	(83	)	6,886
Total	$	7,969	4	(83	)	7,890