Stock Plans (Details 1) - Employee Stock Purchase Plan [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Maximum employee contribution to ESPP	$ 25
Maximum employee contribution to ESPP, percent of base compensation	10.00%
Common stock discount purchase price	95.00%
Shares available under employee stock purchase plan (in shares)	4,550,000
Shares purchased under ESPP (in shares)	8,834	8,006	7,734
Proceeds from stock plans	$ 463	$ 457	$ 444
Number of shares available under employee stock purchase plan (in shares)	260,831