Quarterly report pursuant to Section 13 or 15(d)

Share-Based Compensation - Narrative (Details)

v3.8.0.1
Share-Based Compensation - Narrative (Details) - 2011 Incentive Plan [Member] - shares
shares in Millions
1 Months Ended 9 Months Ended
Jan. 31, 2017
Sep. 30, 2017
Feb. 28, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of Additional Shares Authorized 7.8    
Restricted Stock Units (RSUs) [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of Shares Authorized     0.9
Award Vesting Period, Vests Ratably Over Service Period   3 years  
Performance Units [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of Shares Authorized     0.2
Award Vesting Period, Cliff Vesting   3 years  
Performance Units [Member] | Minimum [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Percentage of Target Amount Earned Upon Vesting If Threshold Performance is Met   50.00%  
Performance Units [Member] | Maximum [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Percentage of Target Amount Earned Upon Vesting If Threshold Performance is Met   200.00%