Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Proceeds from Sale and Maturity of Marketable Securities	$ 13,258	$ 5,357	$ 0
Corporate notes and bonds	17,060	26,242
Fair Value
Asset-backed securities	2,507	141
Corporate notes and bonds	9,332	12,974
Total	11,839	13,115
Gross Unrealized Losses
Asset-backed securities	(3)	0
Corporate notes and bonds	(10)	(3)
Total	(13)	(3)
Gross Unrealized Gains
Asset-backed securities	0	0
Corporate notes and bonds	1	10
Total	1	10
Amortized Cost
Asset-backed securities	2,510	141
Corporate notes and bonds	9,341	12,967
Total	$ 11,851	$ 13,108