Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation and Employee Benefits Plan - Fair Value of Stock Options (Details)

v3.6.0.2
Stock-Based Compensation and Employee Benefits Plan - Fair Value of Stock Options (Details) - USD ($)
$ / shares in Units, $ in Millions
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Proceeds from Stock Options Exercised $ 3.6 $ 8.2 $ 0.3
Employee Service Share-based Compensation, Tax Benefit Realized from Exercise of Stock Options $ 5.7 $ 6.1 $ 0.4
Stock Option [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Weighted-average grant date fair value per share     $ 4.03
Risk-free interest rate     1.70%
Dividend yield     0.00%
Expected life (in years)     4 years 6 months 21 days
Volatility     51.00%