| Schedule of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis | 
 The following tables present the balances of financial assets and liabilities measured at fair value on a recurring basis at December 31, 2019 and 2018 (dollars in thousands): 
 
 | 
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 | 
 | 
 | 
 | 
 | 
 | 
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  | 
      | 
Fair Value Measurements at December 31, 2019 using  | 
 
  | 
      | 
  | 
  | 
      | 
Significant  | 
      | 
  | 
  | 
      | 
  | 
  | 
 
  | 
  | 
Quoted Prices in  | 
  | 
Other  | 
  | 
Significant  | 
  | 
  | 
  | 
 
  | 
  | 
Active Markets for  | 
  | 
Observable  | 
  | 
Unobservable  | 
  | 
  | 
  | 
 
  | 
  | 
Identical Assets  | 
  | 
Inputs  | 
  | 
Inputs  | 
  | 
  | 
  | 
 
  | 
  | 
Level 1  | 
  | 
Level 2  | 
  | 
Level 3  | 
  | 
Balance  | 
 
ASSETS  | 
  | 
  | 
    | 
   | 
  | 
    | 
   | 
  | 
    | 
   | 
  | 
    | 
 
AFS securities:  | 
  | 
  | 
    | 
   | 
  | 
    | 
   | 
  | 
    | 
   | 
  | 
    | 
 
U.S. government and agency securities  | 
  | 
$  | 
 —  | 
  | 
$  | 
 4,498  | 
  | 
$  | 
 —  | 
  | 
$  | 
 4,498  | 
 
Obligations of states and political subdivisions  | 
  | 
   | 
 —  | 
  | 
   | 
 442,992  | 
  | 
   | 
 —  | 
  | 
   | 
 442,992  | 
 
Corporate and other bonds(1)  | 
  | 
   | 
 —  | 
  | 
   | 
 263,070  | 
  | 
   | 
 —  | 
  | 
   | 
 263,070  | 
 
Mortgage-backed securities  | 
  | 
   | 
 —  | 
  | 
   | 
 1,231,806  | 
  | 
   | 
 —  | 
  | 
   | 
 1,231,806  | 
 
Other securities  | 
  | 
   | 
 —  | 
  | 
   | 
 3,079  | 
  | 
   | 
 —  | 
  | 
   | 
 3,079  | 
 
Loans held for sale  | 
  | 
   | 
 —  | 
  | 
   | 
 55,405  | 
  | 
   | 
 —  | 
  | 
   | 
 55,405  | 
 
Derivatives:  | 
  | 
   | 
    | 
  | 
   | 
    | 
  | 
   | 
    | 
  | 
   | 
    | 
 
Interest rate swap  | 
  | 
   | 
 —  | 
  | 
   | 
 54,345  | 
  | 
   | 
 —  | 
  | 
   | 
 54,345  | 
 
Fair value hedges  | 
  | 
   | 
 —  | 
  | 
   | 
 182  | 
  | 
   | 
 —  | 
  | 
   | 
 182  | 
 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
 
LIABILITIES  | 
  | 
   | 
    | 
  | 
   | 
    | 
  | 
   | 
    | 
  | 
   | 
    | 
 
Derivatives:  | 
  | 
   | 
    | 
  | 
   | 
    | 
  | 
   | 
    | 
  | 
   | 
    | 
 
Interest rate swap  | 
  | 
$  | 
 —  | 
  | 
$  | 
 54,345  | 
  | 
$  | 
 —  | 
  | 
$  | 
 54,345  | 
 
Cash flow hedges  | 
  | 
   | 
 —  | 
  | 
   | 
 1,147  | 
  | 
   | 
 —  | 
  | 
   | 
 1,147  | 
 
Fair value hedges  | 
  | 
   | 
 —  | 
  | 
   | 
 6,256  | 
  | 
   | 
 —  | 
  | 
   | 
 6,256  | 
 
 
 
 
 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 
  | 
      | 
Fair Value Measurements at December 31, 2018 using  | 
 
  | 
      | 
  | 
  | 
      | 
Significant  | 
      | 
  | 
  | 
      | 
  | 
  | 
 
  | 
  | 
Quoted Prices in  | 
  | 
Other  | 
  | 
Significant  | 
  | 
  | 
  | 
 
  | 
  | 
Active Markets for  | 
  | 
Observable  | 
  | 
Unobservable  | 
  | 
  | 
  | 
 
  | 
  | 
Identical Assets  | 
  | 
Inputs  | 
  | 
Inputs  | 
  | 
  | 
  | 
 
  | 
  | 
Level 1  | 
  | 
Level 2  | 
  | 
Level 3  | 
  | 
Balance  | 
 
ASSETS  | 
  | 
  | 
    | 
   | 
  | 
    | 
   | 
  | 
    | 
   | 
  | 
    | 
 
AFS securities:  | 
  | 
  | 
    | 
   | 
  | 
    | 
   | 
  | 
    | 
   | 
  | 
    | 
 
Obligations of states and political subdivisions  | 
  | 
$  | 
 —  | 
  | 
$  | 
 468,491  | 
  | 
$  | 
 —  | 
  | 
$  | 
 468,491  | 
 
Corporate and other bonds(1)  | 
  | 
   | 
 —  | 
  | 
   | 
 167,696  | 
  | 
   | 
 —  | 
  | 
   | 
 167,696  | 
 
Mortgage-backed securities  | 
  | 
   | 
 —  | 
  | 
   | 
 1,129,865  | 
  | 
   | 
 —  | 
  | 
   | 
 1,129,865  | 
 
Other securities  | 
  | 
   | 
 —  | 
  | 
   | 
 8,769  | 
  | 
   | 
 —  | 
  | 
   | 
 8,769  | 
 
Derivatives:  | 
  | 
   | 
    | 
  | 
   | 
    | 
  | 
   | 
    | 
  | 
   | 
    | 
 
Interest rate swap  | 
  | 
   | 
 —  | 
  | 
   | 
 19,426  | 
  | 
   | 
 —  | 
  | 
   | 
 19,426  | 
 
Fair value hedges  | 
  | 
   | 
 —  | 
  | 
   | 
 1,872  | 
  | 
   | 
 —  | 
  | 
   | 
 1,872  | 
 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
 
LIABILITIES  | 
  | 
   | 
    | 
  | 
   | 
    | 
  | 
   | 
    | 
  | 
   | 
    | 
 
Derivatives:  | 
  | 
   | 
    | 
  | 
   | 
    | 
  | 
   | 
    | 
  | 
   | 
    | 
 
Interest rate swap  | 
  | 
$  | 
 —  | 
  | 
$  | 
 19,426  | 
  | 
$  | 
 —  | 
  | 
$  | 
 19,426  | 
 
Cash flow hedges  | 
  | 
   | 
 —  | 
  | 
   | 
 4,786  | 
  | 
   | 
 —  | 
  | 
   | 
 4,786  | 
 
Fair value hedges  | 
  | 
   | 
 —  | 
  | 
   | 
 1,684  | 
  | 
   | 
 —  | 
  | 
   | 
 1,684  | 
 
 
 | 
(1) | 
Other bonds includes asset-backed securities. | 
  
 | 
| Carrying Values and Estimated Fair Values of the Company's Financial Instruments | 
 The carrying values and estimated fair values of the Company’s financial instruments as of December 31, 2019 and 2018 are as follows (dollars in thousands): 
 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 
  | 
  | 
Fair Value Measurements at December 31, 2019 using  | 
 
  | 
      | 
  | 
  | 
      | 
Quoted Prices  | 
      | 
Significant  | 
      | 
  | 
  | 
      | 
  | 
  | 
 
  | 
  | 
  | 
  | 
  | 
in Active  | 
  | 
Other  | 
  | 
Significant  | 
  | 
  | 
  | 
 
  | 
  | 
  | 
  | 
  | 
Markets for  | 
  | 
Observable  | 
  | 
Unobservable  | 
  | 
Total Fair  | 
 
  | 
  | 
  | 
  | 
  | 
Identical Assets  | 
  | 
Inputs  | 
  | 
Inputs  | 
  | 
Value  | 
 
  | 
  | 
Carrying  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
 
  | 
   | 
Value  | 
  | 
Level 1  | 
  | 
Level 2  | 
  | 
Level 3  | 
  | 
Balance  | 
 
ASSETS  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
 
Cash and cash equivalents  | 
  | 
$  | 
 436,032  | 
  | 
$  | 
 436,032  | 
  | 
$  | 
 —  | 
  | 
$  | 
 —  | 
  | 
$  | 
 436,032  | 
 
AFS securities  | 
  | 
   | 
 1,945,445  | 
  | 
   | 
 —  | 
  | 
   | 
 1,945,445  | 
  | 
   | 
 —  | 
  | 
   | 
 1,945,445  | 
 
HTM securities  | 
  | 
   | 
 555,144  | 
  | 
   | 
 —  | 
  | 
   | 
 585,820  | 
  | 
   | 
 17,683  | 
  | 
   | 
 603,503  | 
 
Restricted stock  | 
  | 
   | 
 130,848  | 
  | 
   | 
 —  | 
  | 
   | 
 130,848  | 
  | 
   | 
 —  | 
  | 
   | 
 130,848  | 
 
Loans held for sale  | 
  | 
   | 
 55,405  | 
  | 
   | 
 —  | 
  | 
   | 
 55,405  | 
  | 
   | 
 —  | 
  | 
   | 
 55,405  | 
 
Net loans  | 
  | 
   | 
 12,568,642  | 
  | 
   | 
 —  | 
  | 
   | 
 —  | 
  | 
   | 
 12,449,505  | 
  | 
   | 
 12,449,505  | 
 
Derivatives:  | 
  | 
   | 
    | 
  | 
   | 
    | 
  | 
   | 
    | 
  | 
   | 
    | 
  | 
   | 
    | 
 
Interest rate swap  | 
  | 
   | 
 54,345  | 
  | 
   | 
 —  | 
  | 
   | 
 54,345  | 
  | 
   | 
 —  | 
  | 
   | 
 54,345  | 
 
Fair value hedges  | 
  | 
   | 
 182  | 
  | 
   | 
 —  | 
  | 
   | 
 182  | 
  | 
   | 
 —  | 
  | 
   | 
 182  | 
 
Accrued interest receivable  | 
  | 
   | 
 52,721  | 
  | 
   | 
 —  | 
  | 
   | 
 52,721  | 
  | 
   | 
 —  | 
  | 
   | 
 52,721  | 
 
BOLI  | 
  | 
   | 
 322,917  | 
  | 
   | 
 —  | 
  | 
   | 
 322,917  | 
  | 
   | 
 —  | 
  | 
   | 
 322,917  | 
 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
 
LIABILITIES  | 
  | 
   | 
    | 
  | 
   | 
    | 
  | 
   | 
    | 
  | 
   | 
    | 
  | 
   | 
    | 
 
Deposits  | 
  | 
$  | 
 13,304,981  | 
  | 
$  | 
 —  | 
  | 
$  | 
 13,349,943  | 
  | 
$  | 
 —  | 
  | 
$  | 
 13,349,943  | 
 
Borrowings  | 
  | 
   | 
 1,513,748  | 
  | 
   | 
 —  | 
  | 
   | 
 1,479,606  | 
  | 
   | 
 —  | 
  | 
   | 
 1,479,606  | 
 
Accrued interest payable  | 
  | 
   | 
 6,108  | 
  | 
   | 
 —  | 
  | 
   | 
 6,108  | 
  | 
   | 
 —  | 
  | 
   | 
 6,108  | 
 
Derivatives:  | 
  | 
   | 
    | 
  | 
   | 
    | 
  | 
   | 
    | 
  | 
   | 
    | 
  | 
   | 
    | 
 
Interest rate swap  | 
  | 
   | 
 54,345  | 
  | 
   | 
 —  | 
  | 
   | 
 54,345  | 
  | 
   | 
 —  | 
  | 
   | 
 54,345  | 
 
Cash flow hedges  | 
  | 
   | 
 1,147  | 
  | 
   | 
 —  | 
  | 
   | 
 1,147  | 
  | 
   | 
 —  | 
  | 
   | 
 1,147  | 
 
Fair value hedges  | 
  | 
   | 
 6,256  | 
  | 
   | 
 —  | 
  | 
   | 
 6,256  | 
  | 
   | 
 —  | 
  | 
   | 
 6,256  | 
 
 
 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 
  | 
      | 
Fair Value Measurements at December 31, 2018 using  | 
 
  | 
  | 
  | 
  | 
  | 
Quoted Prices  | 
  | 
Significant  | 
  | 
  | 
  | 
  | 
  | 
  | 
 
  | 
  | 
  | 
  | 
  | 
in Active  | 
  | 
Other  | 
  | 
Significant  | 
  | 
  | 
  | 
 
  | 
  | 
  | 
  | 
  | 
Markets for  | 
  | 
Observable  | 
  | 
Unobservable  | 
  | 
Total Fair  | 
 
  | 
  | 
  | 
  | 
  | 
Identical Assets  | 
  | 
Inputs  | 
  | 
Inputs  | 
  | 
Value  | 
 
  | 
  | 
Carrying  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
 
  | 
  | 
Value  | 
  | 
Level 1  | 
  | 
Level 2  | 
  | 
Level 3  | 
  | 
Balance  | 
 
ASSETS  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
 
Cash and cash equivalents  | 
  | 
$  | 
 261,199  | 
  | 
$  | 
 261,199  | 
  | 
$  | 
 —  | 
  | 
$  | 
 —  | 
  | 
$  | 
 261,199  | 
 
AFS securities  | 
  | 
   | 
 1,774,821  | 
  | 
   | 
 —  | 
  | 
   | 
 1,774,821  | 
  | 
   | 
 —  | 
  | 
   | 
 1,774,821  | 
 
HTM securities  | 
  | 
   | 
 492,272  | 
  | 
   | 
 —  | 
  | 
   | 
 499,501  | 
  | 
   | 
 —  | 
  | 
   | 
 499,501  | 
 
Restricted stock  | 
  | 
   | 
 124,602  | 
  | 
   | 
 —  | 
  | 
   | 
 124,602  | 
  | 
   | 
 —  | 
  | 
   | 
 124,602  | 
 
Net loans  | 
  | 
   | 
 9,675,162  | 
  | 
   | 
 —  | 
  | 
   | 
 —  | 
  | 
   | 
 9,534,717  | 
  | 
   | 
 9,534,717  | 
 
Derivatives:  | 
  | 
   | 
    | 
  | 
   | 
    | 
  | 
   | 
    | 
  | 
   | 
    | 
  | 
   | 
    | 
 
Interest rate swap  | 
  | 
   | 
 19,426  | 
  | 
   | 
 —  | 
  | 
   | 
 19,426  | 
  | 
   | 
 —  | 
  | 
   | 
 19,426  | 
 
Fair value hedges  | 
  | 
   | 
 1,872  | 
  | 
   | 
 —  | 
  | 
   | 
 1,872  | 
  | 
   | 
 —  | 
  | 
   | 
 1,872  | 
 
Accrued interest receivable  | 
  | 
   | 
 46,062  | 
  | 
   | 
 —  | 
  | 
   | 
 46,062  | 
  | 
   | 
 —  | 
  | 
   | 
 46,062  | 
 
BOLI  | 
  | 
   | 
 263,034  | 
  | 
   | 
 —  | 
  | 
   | 
 263,034  | 
  | 
   | 
 —  | 
  | 
   | 
 263,034  | 
 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
 
LIABILITIES  | 
  | 
   | 
    | 
  | 
   | 
    | 
  | 
   | 
    | 
  | 
   | 
    | 
  | 
   | 
    | 
 
Deposits  | 
  | 
$  | 
 9,970,960  | 
  | 
$  | 
 —  | 
  | 
$  | 
 9,989,788  | 
  | 
$  | 
 —  | 
  | 
$  | 
 9,989,788  | 
 
Borrowings  | 
  | 
   | 
 1,756,278  | 
  | 
   | 
 —  | 
  | 
   | 
 1,742,038  | 
  | 
   | 
 —  | 
  | 
   | 
 1,742,038  | 
 
Accrued interest payable  | 
  | 
   | 
 5,284  | 
  | 
   | 
 —  | 
  | 
   | 
 5,284  | 
  | 
   | 
 —  | 
  | 
   | 
 5,284  | 
 
Derivatives:  | 
  | 
   | 
    | 
  | 
   | 
    | 
  | 
   | 
    | 
  | 
   | 
    | 
  | 
   | 
    | 
 
Interest rate swap  | 
  | 
   | 
 19,426  | 
  | 
   | 
 —  | 
  | 
   | 
 19,426  | 
  | 
   | 
 —  | 
  | 
   | 
 19,426  | 
 
Cash flow hedges  | 
  | 
   | 
 4,786  | 
  | 
   | 
 —  | 
  | 
   | 
 4,786  | 
  | 
   | 
 —  | 
  | 
   | 
 4,786  | 
 
Fair value hedges  | 
  | 
   | 
 1,684  | 
  | 
   | 
 —  | 
  | 
   | 
 1,684  | 
  | 
   | 
 —  | 
  | 
   | 
 1,684  | 
 
 
 |