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v3.20.2

Loans - Additional Information (Detail) $ in Thousands | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2020 USD ($) Item | Jun. 30, 2019 USD ($) | Jun. 30, 2020 USD ($) Item | Jun. 30, 2019 USD ($) | Dec. 31, 2019 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Concentration of loans in a single industry in excess of ten percent | 0.00% |  | 0.00% |  |
Maximum percentage loan related to single industry | 10.00% |  | 10.00% |  |
Loans and Leases Receivable, Related Parties | $ 314,200 |  | $ 314,200 |  | $ 298,500
Number Of COVID-19 Loan Deferments At Period-End | Item | 3,100 |  | 3,100 |  |
COVID 19 Loan Deferment | $ 2,100,000 |  | $ 2,100,000 |  |
Financing Receivable, Threshold Period Past Due | 90 days |  | 90 days |  |
Texas Leading Index economic condition indicator | 106.7 |  | 106.7 |  | 127.9
Non Accrual Loans [Member] |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Additional interest that would have been recognized on non-accrual loans, net of tax | $ 570 | $ 1,100 | $ 1,600 | $ 2,100 |
Commercial and Industrial Total Energy Loans [Member] |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Percentage of total energy loans to total loans | 7.90% |  | 7.90% |  | 11.20%
Percentage of total energy loans to total loans excluding PPP Loans | 9.60% |  | 9.60% |  |
Commitments to Extend Credit [Member] | Commercial and industrial, Energy [Member] |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Unfunded balances | $ 982,600 |  | $ 982,600 |  |
Standby Letters of Credit [Member] | Commercial and industrial, Energy [Member] |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Unfunded balances | 63,000 |  | 63,000 |  |
Loans Receivable [Member] |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Interest Receivable | $ 39,900 |  | $ 39,900 |  | $ 45,500

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