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Loans and Loans Held for Sale - Additional Information (Details) $ in Thousands | 3 Months Ended | 6 Months Ended | 12 Months Ended
--- | --- | --- | ---
Jun. 30, 2017 USD ($) contract tdr loan | Jun. 30, 2016 tdr loan | Jun. 30, 2017 USD ($) contract tdr loan | Jun. 30, 2016 USD ($) tdr loan | Dec. 31, 2016 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Loans, net of unearned income | $ 4,500 |  | $ 4,500 |  | $ 5,200
Loans, net of discount related to purchase accounting adjustments | 4,900 |  | 4,900 |  | 7,100
Loans receivable, net | $ 5,780,939 |  | 5,780,939 |  | $ 5,615,212
Maximum concentration of commercial real estate and commercial construction portfolio in loans (in excess of) |  |  |  |  | 7.00%
Increase in loans held for sale during the period |  |  | $ 19,300 |  |
Threshold period of satisfactory performance for troubled debt restructuring to be restored to accruing status |  |  | 6 months |  |
Number of troubled debt restructuring loans returned back to accruing status | tdr | 1 | 0 | 1 | 0 |
Amount of troubled debt restructuring loans returned to accruing status | $ 2,000 |  | $ 2,000 |  |
Number of loans modified not considered to be troubled debt restructuring | contract |  |  | 12 |  |
Loans modified not considered to be troubled debt restructuring |  |  | $ 11,800 |  |
Commitment to lend additional funds on troubled debt restructuring | $ 600 |  | $ 600 |  |
Minimum period of loan payment defaults following restructure for TDRs to be in default |  |  | 90 days |  |
Number of troubled debt restructuring loans that defaulted | loan | 0 | 0 | 0 |  |
Commercial |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Percentage of commercial loans in total portfolio loans | 78.00% |  | 78.00% |  | 78.00%
Commercial Loans | $ 4,492,679 |  | $ 4,492,679 |  | $ 4,355,395
Maximum concentration of commercial real estate and commercial construction portfolio in loans (in excess of) | 7.00% |  | 7.00% |  | 7.00%
Increase in loans held for sale during the period |  |  | $ 18,000 |  |
Number of loans held-for-sale sold during period | contract |  |  | 3 |  |
Commercial Real Estate |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Loans receivable, net | $ 2,664,642 |  | $ 2,664,642 |  | $ 2,498,476
Number of loans modified not considered to be troubled debt restructuring | contract |  |  | 3 |  |
Loans modified not considered to be troubled debt restructuring |  |  | $ 1,400 |  |
Commercial Real Estate | Commercial |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Commercial Loans | 2,664,642 |  | 2,664,642 |  | 2,498,476
Commercial and Industrial |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Loans receivable, net | $ 1,401,283 |  | $ 1,401,283 |  | 1,401,035
Number of loans modified not considered to be troubled debt restructuring | contract | 2 |  | 9 |  |
Loans modified not considered to be troubled debt restructuring | $ 3,900 |  | $ 10,400 |  |
Commercial and Industrial | Commercial |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Commercial Loans | 1,401,283 |  | 1,401,283 |  | 1,401,035
Commercial Construction |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Loans receivable, net | 426,754 |  | 426,754 |  | 455,884
Number of troubled debt restructuring loans that defaulted | loan |  |  |  | 1 |
Recorded investment of troubled debt restructuring loans that defaulted |  |  |  | $ 600 |
Commercial Construction | Commercial |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Commercial Loans | 426,754 |  | 426,754 |  | 455,884
Residential Mortgage |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Loans receivable, net | 706,143 |  | 706,143 |  | 701,982
Commercial Real Estate and Commercial Construction | Commercial |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Commercial Loans | $ 3,100,000 |  | $ 3,100,000 |  | $ 3,000,000
Combined percentage of commercial real estate and commercial construction in total commercial loans | 69.00% |  | 69.00% |  | 68.00%
Combined percentage of commercial real estate and commercial construction in total portfolio loans | 54.00% |  | 54.00% |  | 53.00%
Concentration risk percentage of commercial real estate and commercial construction |  |  | 0.00% |  | 0.00%
Out of market exposure of combined portfolio (percent) | 5.30% |  | 5.30% |  | 5.20%
Percentage of total loans out-of-state excluding contiguous states | 2.80% |  | 2.80% |  | 2.70%
Integrity Bancshares, Inc. |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Loans receivable, net | $ 443,000 |  | $ 443,000 |  | $ 543,000
Decrease in acquired loans during the period |  |  |  |  |
Integrity Bancshares, Inc. | Commercial Real Estate |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Loans receivable, net | 231,000 |  | 231,000 |  | 273,000
Integrity Bancshares, Inc. | Commercial and Industrial |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Loans receivable, net | 109,000 |  | 109,000 |  | 141,000
Integrity Bancshares, Inc. | Commercial Construction |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Loans receivable, net | 18,700 |  | 18,700 |  | 33,000
Integrity Bancshares, Inc. | Residential Mortgage |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Loans receivable, net | 64,400 |  | 64,400 |  | 74,000
Integrity Bancshares, Inc. | Home Equity, Installment and Other Consumer Construction |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Loans receivable, net | $ 19,900 |  | $ 19,900 |  | $ 22,000

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