Consolidated Statements of Stockholders' Equity (Parentheticals) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Nonemployee
Share-based compensation expense, stock option awards	$ 579	$ 576	$ 499
Share-based compensation expense, RSU awards	552	370	447
Employee
Share-based compensation expense, stock option awards	7,908	6,728	5,926
Share-based compensation expense, RSU awards	3,364	$ 1,606	$ 163
Adjustments to Additional Paid in Capital, Share-based Compensation, Employee Stock Purchase Program, Requisite Service Period Recognition	$ 412