Quarterly report pursuant to Section 13 or 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) - Deferred stock units [Member]
9 Months Ended
Sep. 30, 2017
shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
2017 351,801
2018 351,796
2021 60,373
2022 166,449
Total 930,419