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Loans and Loans Held for Sale - Additional Information (Details) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2015 USD ($) | Dec. 31, 2016 USD ($) loan | Dec. 31, 2015 USD ($) loan
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Loans and leases receivable, net of deferred income |  | $ 5,200 | $ 3,200
Unamortized discount related to purchase accounting fair value adjustments |  | 7,100 | 10,900
Loans |  | 5,615,212 | 5,062,933
Portfolio loans, net of unearned income |  | 5,611,419 | $ 5,027,612
Decrease in loans held-for-sale during period |  | $ 31,500 |
Number of loan modified | loan |  | 18 |
Number of commitments to lend additional funds on TDRs | loan |  | 1 |
Commitment to lend additional funds on TDRs |  | $ 800 |
Number of TDRs returned back to accruing status | loan |  | 5 | 8
Financial receivable trouble debt restructuring reclassified to accruing trouble debt restructuring status |  | $ 900 | $ 400
Minimum period of loan payment defaults following restructure for TDRs to be in default |  | 90 days |
Number of defaulted TDRs that were restructured withing twelve months prior to defaulting | loan |  | 0 | 0
Increase in nonperforming assets |  | $ 7,600 |
Nonperforming assets |  | $ 43,314 | $ 35,736
Commercial |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Percentage of commercial loans in total portfolio loans |  | 78.00% | 76.00%
Loans and leases receivable, gross |  | $ 4,355,395 | $ 3,836,877
Portfolio loans, net of unearned income |  | 4,355,395 | 3,836,877
Commercial Real Estate |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Loans |  | 2,498,476 | 2,166,603
Portfolio loans, net of unearned income |  | $ 2,498,476 | 2,166,603
Number of loan modified | loan |  | 3 |
Loans modified not considered to be troubled debt restructuring |  | $ 3,100 |
Commercial Real Estate | Commercial |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Loans and leases receivable, gross |  | 2,498,476 | 2,166,603
Portfolio loans, net of unearned income |  | 2,498,476 | 2,166,603
Commercial and Industrial |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Loans |  | 1,401,035 | 1,256,830
Portfolio loans, net of unearned income |  | $ 1,401,035 | 1,256,830
Number of loan modified | loan |  | 15 |
Loans modified not considered to be troubled debt restructuring |  | $ 25,600 |
Commercial and Industrial | Commercial |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Loans and leases receivable, gross |  | 1,401,035 | 1,256,830
Portfolio loans, net of unearned income |  | 1,401,035 | 1,256,830
Commercial Construction |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Loans |  | 455,884 | 413,444
Portfolio loans, net of unearned income |  | 455,884 | 413,444
Commercial Construction | Commercial |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Loans and leases receivable, gross |  | 455,884 | 413,444
Portfolio loans, net of unearned income |  | 455,884 | 413,444
Residential Mortgage |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Loans |  | 701,982 | 639,372
Portfolio loans, net of unearned income |  | 1,190,172 | 1,116,796
Home Equity |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Loans |  | 482,284 | 470,845
Installment and Other Consumer |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Decrease in loans held-for-sale during period | $ (25,000) |  |
Gain on sale of credit card portfolio |  |  | 2,100
Consumer Construction |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Loans |  | $ 5,906 | $ 6,579
CRE and Commercial Construction |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Out-of-state exposure of combined portfolio |  | 5.20% | 5.80%
Percentage of total loans out-of-state |  | 2.70% | 3.00%
CRE and Commercial Construction | Commercial |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Loans and leases receivable, gross |  | $ 3,000,000 |
Combined percentage of commercial real estate and commercial construction in total commercial loans |  | 68.00% | 67.00%
Combined percentage of commercial real estate and commercial construction in total portfolio loans |  | 53.00% | 51.00%
Portfolio loans, net of unearned income |  |  | $ 2,600,000
Concentration risk percentage |  | 0.00% | 0.00%
Maximum concentration of commercial real estate and commercial construction portfolio in loans |  | 7.00% | 7.00%
Integrity Bancshares, Inc. |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Loans |  | $ 543,300 | $ 673,300
Nonperforming assets, assumed in business acquisitions |  | 16,900 |
Integrity Bancshares, Inc. | Commercial Real Estate |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Loans |  | 273,000 | 293,200
Integrity Bancshares, Inc. | Commercial and Industrial |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Loans |  | 140,800 | 167,700
Integrity Bancshares, Inc. | Commercial Construction |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Loans |  | 33,500 | 69,200
Integrity Bancshares, Inc. | Residential Mortgage |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Loans |  | 74,000 | 115,600
Integrity Bancshares, Inc. | Home Equity, Installment and Other Consumer Construction |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Loans |  | $ 22,000 | $ 27,500

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