XML 142 R118.htm IDEA: XBRL DOCUMENT v3.8.0.1
Share-Based Compensation - Additional Information (Detail)
 12 Months Ended
Nov. 14, 2016
Dec. 31, 2017
USD ($)
$ / shares
shares
Dec. 31, 2016
USD ($)
$ / shares
Dec. 31, 2015
USD ($)
$ / shares
Stock Based Compensation [Line Items]        
Stock split ratio 1.5      
Share-based compensation, performance awards, performance goals description   The performance shares that are awarded become earned and vested based on the achievement of certain performance goals during a performance period as established by the Committee at the time of each grant. The performance goals are based on a comparison of the Company’s average performance over the performance period for the return on common equity, compounded annual growth rate of total assets, and return on average assets, all as relative to the average performance for publicly traded banks with total assets between $1 billion and $5 billion on the SNL Bank Index. Holders of performance share awards receive pass-through dividends but do not have any voting rights before the performance shares are earned and vested.    
Total assets   $ 3,964,303,000 $ 3,141,156,000  
Tax benefit associated with compensation expense   114,000 113,000 $ 101,000
Total compensation cost   325,000 324,000 288,000
Total compensation cost   1,700,000 608,000 643,000
Cash received from option exercise   1,600,000 214,000 403,000
Actual tax benefit realized for the tax deductions   522,000 $ 158,000 $ 151,000
Unrecognized compensation cost   $ 911,000    
Weighted-average period cost over which cost is expected to be recognized   1 year 6 months    
Option Activity Under the 2013 Plan [Member]        
Stock Based Compensation [Line Items]        
Maximum common shares issued under the plan | shares   1,037,550    
Number of shares available incentive stock options | shares   150,000    
Non-option awards granted | shares   600,000    
Weighted average grant-date fair value of options granted | $ / shares   $ 7.25 $ 3.89 $ 4.09
Option Activity Under the 2003 Plan [Member]        
Stock Based Compensation [Line Items]        
Maximum common shares issued under the plan | shares   506,250    
Number of shares available incentive stock options | shares   506,250    
Non-option awards granted | shares   253,125    
Additional common shares available for issuance | shares   590,625    
Grants vest at the end of   4 years    
Option Activity Under the 2003 Plan [Member] | Minimum [Member]        
Stock Based Compensation [Line Items]        
Grants vest at the end of   3 years    
Option Activity Under the 2003 Plan [Member] | Maximum [Member]        
Stock Based Compensation [Line Items]        
Grants vest at the end of   5 years    
Performance Based Share Awards [Member] | Minimum [Member]        
Stock Based Compensation [Line Items]        
Total assets   $ 1,000,000,000    
Performance Based Share Awards [Member] | Maximum [Member]        
Stock Based Compensation [Line Items]        
Total assets   5,000,000,000    
Restricted and Performance Shares [Member]        
Stock Based Compensation [Line Items]        
Tax benefit associated with compensation expense   47,000 $ 99,000 $ 124,000
Total compensation cost   $ 135,000 $ 284,000 $ 355,000