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Loans Loans - Allowance for Credit Loss By Loan Class Calculated in Accordance With CECL Methodology (Details) - USD ($) $ in Thousands | Jun. 30, 2021 | Mar. 31, 2021 | Dec. 31, 2020 | Jun. 30, 2020 | Mar. 31, 2020 | Dec. 31, 2019
--- | --- | --- | --- | --- | --- | ---
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | $ 255,288 |  | $ 263,177 |  |  |
Commercial Portfolio Segment [Member] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 65,271 | $ 70,892 | 73,843 | $ 98,536 | $ 92,152 | $ 51,593
Commercial and Industrial Total Energy Loans [Member] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 28,010 | 33,472 | 39,553 | 40,817 | 103,201 | 37,382
Commercial Real Estate Portfolio Segment [Member] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 147,993 | 144,440 | 134,892 | 93,425 | 52,319 | 31,037
Total consumer real estate loans [Member] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 6,154 | 5,636 | 7,926 | 8,998 | 8,170 | 4,113
Consumer Loan [Member] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 7,860 | 6,818 | 6,963 | 8,285 | 8,039 | 8,042
Loans Receivable [Member] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 255,288 | $ 261,258 | 263,177 | $ 250,061 | $ 263,881 | $ 132,167
Modeled Expected Credit Losses [Member] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 85,328 |  | 214,552 |  |  |
Modeled Expected Credit Losses [Member] | Commercial Portfolio Segment [Member] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 47,269 |  | 65,645 |  |  |
Modeled Expected Credit Losses [Member] | Commercial and Industrial Total Energy Loans [Member] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 7,754 |  | 8,910 |  |  |
Modeled Expected Credit Losses [Member] | Commercial Real Estate Portfolio Segment [Member] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 17,659 |  | 125,126 |  |  |
Modeled Expected Credit Losses [Member] | Total consumer real estate loans [Member] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 6,057 |  | 7,926 |  |  |
Modeled Expected Credit Losses [Member] | Consumer Loan [Member] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 6,589 |  | 6,945 |  |  |
Q-factor adjustments [Member] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 150,671 |  | 33,346 |  |  |
Q-factor adjustments [Member] | Commercial Portfolio Segment [Member] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 13,509 |  | 2,877 |  |  |
Q-factor adjustments [Member] | Commercial and Industrial Total Energy Loans [Member] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 6,446 |  | 21,216 |  |  |
Q-factor adjustments [Member] | Commercial Real Estate Portfolio Segment [Member] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 129,384 |  | 9,253 |  |  |
Q-factor adjustments [Member] | Total consumer real estate loans [Member] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 61 |  | 0 |  |  |
Q-factor adjustments [Member] | Consumer Loan [Member] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 1,271 |  | 0 |  |  |
Specific Valuation Allowances [Member] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 19,289 |  | 15,279 |  |  |
Specific Valuation Allowances [Member] | Commercial Portfolio Segment [Member] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 4,493 |  | 5,321 |  |  |
Specific Valuation Allowances [Member] | Commercial and Industrial Total Energy Loans [Member] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 13,810 |  | 9,427 |  |  |
Specific Valuation Allowances [Member] | Commercial Real Estate Portfolio Segment [Member] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 950 |  | 513 |  |  |
Specific Valuation Allowances [Member] | Total consumer real estate loans [Member] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 36 |  | 0 |  |  |
Specific Valuation Allowances [Member] | Consumer Loan [Member] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | $ 0 |  | $ 18 |  |  |

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