XML 253 R57.htm IDEA: XBRL DOCUMENT v3.19.3
Performance Awards - Additional Information (Detail) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]        
Unrecognized compensation expense $ 1.6   $ 1.6  
Performance Awards        
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]        
Compensation expense (benefit) $ 0.4 $ (1.0) $ 1.1 $ 1.6
Unrecognized compensation expense   $ 1.6   $ 1.6
2014 Equity Incentive Plan | Performance Awards        
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]        
Performance period     3 years