Annual report pursuant to Section 13 and 15(d)

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

v3.10.0.1
Note 1 - Summary of Significant Accounting Policies (Details Textual) - USD ($)
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Jan. 01, 2019
Number of Reporting Units 1      
Unrecognized Tax Benefits Threshold Percentage 50.00%      
Advertising Expense $ 557,000 $ 716,000 $ 544,000  
Accumulated Other Comprehensive Income (Loss), Net of Tax, Total $ (4,741,000) $ (198,000)    
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent 21.00% 35.00% 35.00%  
Income Tax Expense (Benefit), Total $ 31,902,000 $ 44,258,000 $ 29,339,000  
Accounting Standards Update 2014-09 [Member] | Reclassification of Noninterest Income and Noninterest Expense to Net Against Interchange Fees for Credit and Debit Cards [Member] | Twelve Months Ended December 31, 2017 [Member]        
Prior Period Reclassification Adjustment 1,700,000      
Accounting Standards Update 2014-09 [Member] | Reclassification of Noninterest Income and Noninterest Expense to Net Against Interchange Fees for Credit and Debit Cards [Member] | Twelve Months Ended December 31, 2016 [Member]        
Prior Period Reclassification Adjustment 1,100,000      
Adjustments for New Accounting Principle, Early Adoption [Member]        
Accumulated Other Comprehensive Income (Loss), Net of Tax, Total   43,000    
Accounting Standards Update 2016-09 [Member]        
Income Tax Expense (Benefit), Total $ (3,900,000) (4,600,000) $ (4,800,000)  
Metro Bancshares, Inc [Member]        
Finite-Lived Intangible Assets, Remaining Amortization Period 7 years      
Goodwill, Ending Balance $ 13,600,000      
Minimum [Member]        
Property, Plant and Equipment, Useful Life 3 years      
Minimum [Member] | Accounting Standards Update 2016-02 [Member] | Subsequent Event [Member]        
Operating Lease, Right-of-Use Asset       $ 13,000,000
Operating Lease, Liability, Total       15,000,000
Maximum [Member]        
Property, Plant and Equipment, Useful Life 39 years 182 days      
Maximum [Member] | Accounting Standards Update 2016-02 [Member] | Subsequent Event [Member]        
Operating Lease, Right-of-Use Asset       16,000,000
Operating Lease, Liability, Total       $ 17,000,000
Federal Reserve Bank [Member]        
Cash Reserve Deposit Required and Made $ 51,000,000 $ 51,800,000