Quarterly report pursuant to Section 13 or 15(d)

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

v3.8.0.1
Stock-Based Awards Stock-Based Awards (Summary of Stock-Based Awards Granted) (Details)
$ / shares in Units, $ in Millions
9 Months Ended
Sep. 30, 2017
USD ($)
$ / shares
Rate
shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant 10,200,000
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 | $ / shares $ 6.36
Restricted stock units (in shares)  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Number of Awards Granted (in shares) 359,097
Weighted Average per Share Fair Value | $ / shares $ 37.41
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 | $ / shares $ 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) 54,159
Weighted Average per Share Fair Value | $ / shares $ 8.10
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) 22,309
Maximum [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 | Rate 200.00%
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 | Rate 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 | Rate 0.00%