Quarterly report pursuant to Section 13 or 15(d)

Stock-based Compensation Plans and Awards - Schedule of assumptions used for determining the per-share fair value (Details)

v3.5.0.2
Stock-based Compensation Plans and Awards - Schedule of assumptions used for determining the per-share fair value (Details) - Employee stock - Black Scholes Options Pricing Model
3 Months Ended 6 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Jun. 30, 2016
Jun. 30, 2015
Assumptions used to calculate per-share fair value of award        
Expected life (in years) 15 days 15 days 15 days 15 days
Risk-free interest rate 0.41% 0.07%    
Expected volatility 41.00% 42.00% 41.00% 42.00%
Expected dividend yield 0.00% 0.00% 0.00% 0.00%
Minimum        
Assumptions used to calculate per-share fair value of award        
Risk-free interest rate     0.24% 0.05%
Maximum        
Assumptions used to calculate per-share fair value of award        
Risk-free interest rate     0.41% 0.07%