Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation Plans - Schedule of Future Share Settlements (Detail)

v3.8.0.1
Stock-Based Compensation Plans - Schedule of Future Share Settlements (Detail) - 2013 Omnibus Equity Incentive Plan [Member] - Deferred stock units [Member] - shares
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
2018 237,052  
2021 60,373  
2022 281,193  
Total 578,618 930,419