v3.10.0.1
Share-Based Payments - Total Shareholder Return Units Activity (Details) - Total Shareholder Return Units (TSRUs) [Member]
shares in Thousands
12 Months Ended
Oct. 26, 2016
Employee
Dec. 31, 2018
Employee
$ / shares
shares
Dec. 31, 2017
$ / shares
shares
Dec. 31, 2016
$ / shares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]        
Nonvested, beginning of period, shares | shares   103,906    
Granted, shares | shares   47,755    
Vested, shares | shares [1]   (7,203)    
Forfeited, shares | shares   (5,512)    
Nonvested, end of period, shares | shares   138,945 103,906  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]        
Nonvested, beginning of period, weighted-average grant date fair value per share (in dollars per share)   $ 6.07    
Granted, weighted-average grant-date fair value per share (in dollars per share)   7.42 $ 6.23 $ 5.83
Vested, weighted-average grant date fair value per share (in dollars per share) [1]   6.67    
Forfeited, weighted-average grant date fair value per share (in dollars per share)   6.55    
Nonvested, end of period, weighted-average grant date fair value per share (in dollars per share)   6.48 6.07  
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Outstanding, Weighted Average Grant Price [Abstract]        
Outstanding, beginning of period, weighted-average exercise price per share (in dollars per share)   32.47    
Granted, weighted-average exercise price per share (in dollars per share)   35.75    
Forfeited, weighted-average exercise price per share (in dollars per share) [1]   34.49    
Expired, weighted-average exercise price per share (in dollars per share)   33.88    
Outstanding, end of period, weighted-average exercise price per share (in dollars per share)   $ 33.44 $ 32.47  
Number of shares modified to accelerate vesting | shares   1,700    
Number of employees affected by plan modification | Employee 2,900 260    
[1] Includes the modification of approximately 1.7 million TSRUs to approximately 260 employees, including management employees, in connection with our Organizing for Growth initiative. The terms were modified to permit the vesting upon termination. The impact to compensation expense was immaterial.