Goodwill and Other Intangible Assets (Tables)
 12 Months Ended
Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]  
Schedule of Goodwill [Table Text Block]

The change in goodwill during the year is as follows (dollars in thousands):

    2016   2015    
Beginning of year   $ 145,909      $ 145,909    
Acquired goodwill     -     -    
Impairment     -     -    
End of year   $ 145,909   $ 145,909    
Intangible Assets Disclosure [Text Block]

The table below provides information regarding the carrying amounts and accumulated amortization of total amortized intangible assets as of the dates set forth below. 

    Gross
Carrying
Amount		   Accumulated
Amortization		   Net
Carrying
Amount		  
    (dollars in thousands)  
As of December 31, 2016:                    
                       
Core deposit intangibles   $ 6,011   $ (2,923)   $  3,088    
                     
As of December 31, 2015:                    
                     
Core deposit intangibles   $ 6,011   $ (2,103)   $ 3,908  
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]

Aggregate amortization expense was $820,000, $917,000 and $507,000 for 2016, 2015 and 2014, respectively. Estimated amortization expense for each of the next five years (in thousands):

2017  $724 
2018   627 
2019   531 
2020   434 
2021   338