Annual report pursuant to Section 13 and 15(d)

Note 1 - Summary of Significant Accounting Policies (Details Textual)

v3.8.0.1
Note 1 - Summary of Significant Accounting Policies (Details Textual) - USD ($)
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Number of Reporting Units   1    
Unrecognized Tax Benefits Threshold Percentage   50.00%    
Advertising Expense   $ 716,000 $ 544,000 $ 562,000
Income Tax Expense (Benefit)   44,258,000 29,339,000 $ 25,465,000
Accumulated Other Comprehensive Income (Loss), Net of Tax   $ 198,000 $ 624,000  
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent   35.00% 35.00% 35.00%
Retained Earnings (Accumulated Deficit)   $ 389,554,000 $ 307,151,000  
Scenario, Forecast [Member]        
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent 21.00%      
Accounting Standards Update 2016-09 [Member]        
Income Tax Expense (Benefit)   (4,600,000) (4,800,000)  
Adjustments for New Accounting Principle, Early Adoption [Member]        
Accumulated Other Comprehensive Income (Loss), Net of Tax   43,000    
Retained Earnings (Accumulated Deficit)   $ 43,000    
Metro Bancshares, Inc [Member]        
Finite-Lived Intangible Assets, Remaining Amortization Period   7 years    
Goodwill   $ 13,600,000    
Minimum [Member]        
Property, Plant and Equipment, Useful Life   3 years    
Maximum [Member]        
Property, Plant and Equipment, Useful Life   39 years 182 days    
Federal Reserve Bank [Member]        
Cash Reserve Deposit Required and Made   $ 51,800,000 $ 39,200,000