Quarterly report pursuant to Section 13 or 15(d)

Equity - Additional Information (Detail)

v3.5.0.2
Equity - Additional Information (Detail) - USD ($)
3 Months Ended 9 Months Ended
Sep. 30, 2016
Sep. 30, 2015
Sep. 30, 2016
Sep. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Amount of potential offer and sale of securities     $ 13,914,000 $ 10,794,000
Maximum [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Amount of potential offer and sale of securities     $ 500,000,000  
Restricted Common Stock [Member] | 2013 Plan [Member] | Employees and Directors [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Shares awarded     367,753  
Restricted Common Stock [Member] | 2013 Plan [Member] | Employees and Directors [Member] | Maximum [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Restricted common shares vesting years     2019  
Restricted Common Stock [Member] | 2013 Plan [Member] | Employees and Directors [Member] | Minimum [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Restricted common shares vesting years     2016  
Restricted Common Stock [Member] | 2013 Plan [Member] | Certain Employees [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Shares awarded     291,000  
Restricted Incentive [Member] | 2013 Plan [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Equity-based compensation expense $ 3,000,000 $ 3,000,000 $ 7,000,000 $ 8,000,000
Unrecognized compensation expense 12,000,000   $ 12,000,000  
Weighted-average term in which unrecognized compensation expense is expected to be recognized     2 years  
Assumed forfeiture rate for calculation of equity-based compensation expense     5.00%  
Restricted Incentive [Member] | 2013 Plan [Member] | Maximum [Member] | Accounting Standards Update 2016-09 [Member] | Retained Earnings [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Adjustment to retained earnings for the equity based compensation expense $ 1,000,000   $ 1,000,000