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Summary of Significant Accounting Policies (Details) $ in Thousands |  | 12 Months Ended |  |  |
--- | --- | --- | --- | --- | ---
Jan. 01, 2020 USD ($) | Dec. 31, 2020 USD ($) segment | Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($)
Basis Of Presentation [Line Items] |  |  |  |  |
Cash and cash equivalents |  |  | $ 111,500 |  |
Federal funds sold |  | $ 158,700 | 87,800 |  |
Number of reportable segments | segment |  | 3 |  |  |
Federal Reserve Bank stock |  | $ 142,500 | 141,700 |  |
Required percent of capital or surplus |  | 6.00% |  |  |
Required percent of deposits |  | 0.60% |  |  |
Federal Home Loan Bank stock |  | $ 15,000 | 144,700 |  |
Vesting period |  | 3 years |  |  |
Financing Receivable, Allowance for Credit Loss | $ 281,402 | $ 605,736 | 281,402 | $ 250,555 | $ 249,268
Reserve for Unfunded Commitments | 1,375 | 47,800 |  |  |
All Financing Receivable, Allowance for Credit Loss | 282,777 | 653,500 |  |  |
Loans, net | 36,881,048 |  |  |  |
Retained earnings | 1,068,327 | 1,178,019 | 1,068,327 |  |
Total shareholders’ equity |  | 5,161,334 | 4,941,690 | 3,133,602 | 2,961,566
Deferred fees and costs, net |  | 77,700 | 25,400 |  |
Accounting Standards Update 2016-02 |  |  |  |  |
Basis Of Presentation [Line Items] |  |  |  |  |
Financing Receivable, Allowance for Credit Loss |  | 364,396 |  |  |
Reserve for Unfunded Commitments |  | 28,815 |  |  |
All Financing Receivable, Allowance for Credit Loss |  | 393,211 |  |  |
Loans, net |  | 36,860,281 |  |  |
Retained earnings |  | 1,032,606 |  |  |
Cumulative Effect, Period of Adoption, Adjustment |  |  |  |  |
Basis Of Presentation [Line Items] |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 82,994 |  |  |  |
Reserve for Unfunded Commitments | 27,440 |  |  |  |
All Financing Receivable, Allowance for Credit Loss | 110,434 |  |  |  |
Loans, net | (20,767) |  |  |  |
Retained earnings | (35,721) |  |  |  |
Total shareholders’ equity |  |  | (35,721) | 4,270 |
Retained Earnings |  |  |  |  |
Basis Of Presentation [Line Items] |  |  |  |  |
Total shareholders’ equity |  | $ 1,178,019 | 1,068,327 | 843,767 | $ 544,207
Retained Earnings | Cumulative Effect, Period of Adoption, Adjustment |  |  |  |  |
Basis Of Presentation [Line Items] |  |  |  |  |
Total shareholders’ equity | 35,700 |  | (35,721) | $ 4,270 |
Non-employee Director |  |  |  |  |
Basis Of Presentation [Line Items] |  |  |  |  |
Vesting period |  | 3 years |  |  |
Non-employee |  |  |  |  |
Basis Of Presentation [Line Items] |  |  |  |  |
Vesting period |  | 3 years |  |  |
Consumer mortgages |  |  |  |  |
Basis Of Presentation [Line Items] |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 68,190 |  |  |  |
Consumer mortgages | Accounting Standards Update 2016-02 |  |  |  |  |
Basis Of Presentation [Line Items] |  |  |  |  |
Financing Receivable, Allowance for Credit Loss |  | $ 154,145 |  |  |
Consumer mortgages | Cumulative Effect, Period of Adoption, Adjustment |  |  |  |  |
Basis Of Presentation [Line Items] |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 85,955 |  |  |  |
Unfunded Loan Commitment |  |  |  |  |
Basis Of Presentation [Line Items] |  |  |  |  |
Financing Receivable, Purchased with Credit Deterioration, Amount at Purchase Price | 62,200 |  |  |  |
Financing Receivable, Allowance for Credit Loss |  |  | $ 1,400 |  |
Total commercial and industrial |  |  |  |  |
Basis Of Presentation [Line Items] |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 145,782 |  |  |  |
Total commercial and industrial | Accounting Standards Update 2016-02 |  |  |  |  |
Basis Of Presentation [Line Items] |  |  |  |  |
Financing Receivable, Allowance for Credit Loss |  | 143,472 |  |  |
Total commercial and industrial | Cumulative Effect, Period of Adoption, Adjustment |  |  |  |  |
Basis Of Presentation [Line Items] |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | (2,310) |  |  |  |
Total commercial real estate |  |  |  |  |
Basis Of Presentation [Line Items] |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 67,430 |  |  |  |
Total commercial real estate | Accounting Standards Update 2016-02 |  |  |  |  |
Basis Of Presentation [Line Items] |  |  |  |  |
Financing Receivable, Allowance for Credit Loss |  | 66,779 |  |  |
Total commercial real estate | Cumulative Effect, Period of Adoption, Adjustment |  |  |  |  |
Basis Of Presentation [Line Items] |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | $ (651) |  |  |  |
Payment Protection Program Loans |  |  |  |  |
Basis Of Presentation [Line Items] |  |  |  |  |
Deferred fees and costs, net |  | $ (48,900) |  |  |
DRR Methodology |  |  |  |  |
Basis Of Presentation [Line Items] |  |  |  |  |
Loans, net |  | 40.00% | 45.00% |  |
Maximum |  |  |  |  |
Basis Of Presentation [Line Items] |  |  |  |  |
Other intangible assets, useful life |  | 10 years |  |  |
Maximum | Buildings and improvements |  |  |  |  |
Basis Of Presentation [Line Items] |  |  |  |  |
Premises and equipment, useful life |  | 40 years |  |  |
Maximum | Furniture, equipment and software |  |  |  |  |
Basis Of Presentation [Line Items] |  |  |  |  |
Premises and equipment, useful life |  | 10 years |  |  |
Maximum | Software and Software Development Costs |  |  |  |  |
Basis Of Presentation [Line Items] |  |  |  |  |
Premises and equipment, useful life |  | 7 years |  |  |
Minimum |  |  |  |  |
Basis Of Presentation [Line Items] |  |  |  |  |
Other intangible assets, useful life |  | 8 years |  |  |
Minimum | Buildings and improvements |  |  |  |  |
Basis Of Presentation [Line Items] |  |  |  |  |
Premises and equipment, useful life |  | 10 years |  |  |
Minimum | Furniture, equipment and software |  |  |  |  |
Basis Of Presentation [Line Items] |  |  |  |  |
Premises and equipment, useful life |  | 3 years |  |  |
Minimum | Software and Software Development Costs |  |  |  |  |
Basis Of Presentation [Line Items] |  |  |  |  |
Premises and equipment, useful life |  | 3 years |  |  |

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