Stock Plans Stock Plans (Schedule of RSU Expense by Vesting Type) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 1,203	$ 839
Restricted stock unit awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	736	305
Restricted stock unit awards | Service-based
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	533	212
Performance restricted stock unit awards | Performance-based specific objectives
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	12	59
Performance restricted stock unit awards | Market-condition
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 191	$ 34