Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Awards Stock-Based Awards (Summary of Stock-Based Awards Granted) (Details)

v3.7.0.1
Stock-Based Awards Stock-Based Awards (Summary of Stock-Based Awards Granted) (Details) - USD ($)
$ / shares in Units, $ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2017
Jun. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Restricted Stock Award, Forfeitures $ 4.5  
Stock appreciation rights (in shares)    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Number of Awards Granted (in shares)   1,144,049
Weighted Average per Share Fair Value   $ 6.36
Restricted stock units (in shares)    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Number of Awards Granted (in shares)   349,144
Weighted Average per Share Fair Value   $ 37.45
Performance Shares (in shares)    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Number of Awards Granted (in shares)   96,439
Weighted Average per Share Fair Value   $ 57.36
Employee stock purchase plan options (in shares)    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Number of Awards Granted (in shares)   31,729
Weighted Average per Share Fair Value   $ 8.63
Dividend equivalents due to quarterly dividend (in shares)    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Number of Awards Granted (in shares)   15,119
Maximum [Member] | Performance Shares (in shares)    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage   200.00%
Minimum [Member] | Stock appreciation rights (in shares)    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage   200.00%
Minimum [Member] | Performance Shares (in shares)    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage   0.00%