Stock-Based Compensation (Schedule of Nonvested Restricted Stock Units Activity) (Details) (USD $)
12 Months Ended
Dec. 31, 2014
Number of shares  
Nonvested as of January 1, 2014 354,270
Granted 602,422
Exercised / Released (154,249)
Canceled / forfeited (7,970)
Nonvested as of December 31, 2014 794,473
Weighted- average grant date fair value per share  
Nonvested as of January 1, 2014 $ 9.41
Granted $ 4.80
Exercised / Released $ 5.98
Canceled / forfeited $ 5.81
Nonvested as of December 31, 2014 $ 6.62