Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation Plans - Amendments to Restricted Stock and SARs - Additional Information (Detail)

v3.7.0.1
Stock-Based Compensation Plans - Amendments to Restricted Stock and SARs - Additional Information (Detail) - shares
 3 Months Ended 12 Months Ended
Mar. 31, 2017
Dec. 31, 2016
Deferred stock units [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Employee termination age   67 years
DSU settlement to common stock percentage   20.00%
DSU settlement into actual stock issued term   5 years
Percentage of shares of deferred stock units settled in the event of death or termination after reaching age 67   100.00%
Restricted Stock Sales Restriction [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Sales restriction lapse percentage for restricted stock 20.00%  
Employee termination age 67 years  
Sales restriction period for restricted stock 5 years  
Percentage of shares of stock released from resale restriction upon consummation of change of control 100.00%  
Percentage of shares of restricted released from resale restriction in the event of death or termination after reaching age 67 100.00%  
Number of original shares subject to resale restriction 3,689,326  
Number of shares remain subject to sales restriction 1,475,730