Quarterly report pursuant to Section 13 or 15(d)

Equity - Additional Information (Detail)

v3.7.0.1
Equity - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Millions
3 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Restricted stock and restricted stock units [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Stock units granted 253,200  
Stock units granted average price $ 18.99  
Restricted stock and restricted stock units [Member] | 2013 Plan [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Equity-based compensation expense $ 3 $ 2
Unrecognized compensation expense $ 20  
Weighted-average term in which unrecognized compensation expense is expected to be recognized 2 years  
Restricted stock and restricted stock units [Member] | Employees and Directors [Member] | 2013 Plan [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Shares awarded 701,982  
Restricted stock and restricted stock units [Member] | Employees and Directors [Member] | 2013 Plan [Member] | Minimum [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Restricted common shares vesting years 2017  
Restricted stock and restricted stock units [Member] | Employees and Directors [Member] | 2013 Plan [Member] | Maximum [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Restricted common shares vesting years 2020  
Performance Based Restricted Stock Award [Member] | Employees and Directors [Member] | 2013 Plan [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Stock units granted 4,800,000  
Stock units granted average price $ 18.99