Equity Compensation (Fair Value) (Details) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Stock options    
Total fair value for the awards vested during the period $ 1,100  
Stock options    
Intrinsic-value    
Options Exercised 3,119 $ 76
Options Exercisable 14,761 4,698
Options Vested and Expected to Vest $ 16,121 $ 4,715