Stockholders' Equity (Summary of the Changes in Stockholders' Equity) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Stockholders’ equity at the beginning of period			$ 295,510
Net loss	$ 6,895	$ (6,647)	9,384	$ (7,312)
Accumulated other comprehensive loss			(215)
Exercise of stock options			3,253
Issuance of common stock to employees under ESPP			915
Repurchase of common stock			(1,242)
Purchase of treasury stock			(8,190)
Stockholders’ equity at the end of period	$ 307,464		307,464
Nonemployee
Share-based compensation expense			815
Employee
Share-based compensation expense			$ 7,234