XML 95 R81.htm IDEA: XBRL DOCUMENT v3.10.0.1
Stock-Based Compensation - Additional Information (Detail)
9 Months Ended
Sep. 30, 2018
USD ($)
Category
shares
Dec. 31, 2017
USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Authorizes issuance of common stock 4,350,000  
Number of shares available for grant 2,100,000  
Maximum shares that may be used as full value awards 1,200,000  
Amount of unrecognized stock-based compensation cost | $ $ 7,300,000  
Weighted average period for recognition 1 year 10 months 6 days  
Capitalized share based compensation cost | $ $ 0 $ 0
Minimum [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Vesting period 3 years  
RSUs [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Vesting period 3 years  
PSUs [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Vesting period 3 years  
Number of individual categories | Category 3  
PSUs [Member] | Upon certain Return on Invested Capital targets for 2016 to 2018 units [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Vesting percentage 40.00%  
PSUs [Member] | Upon certain Cumulative EPS targets for 2016 to 2018 units [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Vesting percentage 40.00%  
PSUs [Member] | Upon certain market based Shareholder Return targets for 2016 to 2018 units [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Vesting percentage 20.00%  
Employee Stock Option [Member] | Maximum [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expiration period 10 years