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Acquisitions - Schedule of Recognized Identifiable Assets Acquired and Liabilities Assumed (Details) $ / shares in Units, $ in Thousands |  | 12 Months Ended |  |
--- | --- | --- | --- | ---
Feb. 01, 2022 USD ($) office $ / shares shares | Dec. 31, 2023 USD ($) segment | Dec. 31, 2022 USD ($) | Dec. 31, 2021 USD ($)
Business Acquisition [Line Items] |  |  |  |
Goodwill |  | $ 1,100,900 | $ 1,100,900 | $ 621,600
Estimated useful lives of related deposits |  | 12 years |  |
Number of operating segments | segment |  | 1 |  |
Great Western Bank |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Number of banking offices | office | 174 |  |  |
Cash and cash equivalents | $ 2,006,900 |  |  |
Business Combination, Recognized Identifiable Assets Acquirede and Liablilities Assumed, Current Assets, Securities Purchased Under Agreement to Resell | 101,100 |  |  |
business combinatios, recognized identifiable assets acquired and liabilities assumed, loans held | 217,000 |  |  |
Investment securities | 2,699,000 |  |  |
Business Combinations, Recognized Identifiable Assets Acquired And Liabilities Assumed, Loans Held for Investment | 7,705,000 |  |  |
Business Combinations, Recognized Identifiable Assets Acquired and Liabilities Assumed, Loans and Leases Receivable, Allowance | (59,500) |  |  |
Premises and equipment | 144,700 |  |  |
Business Combinations, Recognized Identifiable Assests Acquired and Liabilities Assumed Other Real Estate Owned | 15,800 |  |  |
Company owned life insurance | 186,600 |  |  |
Core deposit intangible assets | 50,100 |  |  |
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill | 22,800 |  |  |
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Mortgage Servicing Rights | 1,300 |  |  |
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets | 60,200 |  |  |
Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Other Assets | 200,800 |  |  |
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed, Accounts Payable And Accrued Expense | 110,400 |  |  |
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Federal Home Loan Bank Advances | 122,900 |  |  |
Total assets acquired | 13,351,800 |  |  |
Deposits | 11,688,000 |  |  |
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed, Other Liabilities | 36,400 |  |  |
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Financial Liabilities | 76,100 |  |  |
Total liabilities assumed | 12,107,800 |  |  |
Net assets acquired | 1,244,000 |  |  |
Class A common stock | 1,723,300 |  |  |
Total consideration paid | 1,723,300 |  |  |
Goodwill | 479,300 |  |  |
Buisness Combination, Recognizable Assets Acquired and Liabilities Assumed, Securities Sold Under Repurchase Agreement | 74,000 |  |  |
Business Combination, Consideration Paid in Lieu of Fractional Shares | 13 |  |  |
Business Acquisition, Goodwill, Expected Tax Deductible Amount | $ 31,700 |  |  |
Great Western Bank | Class A Common Stock |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Common stock issued (in shares) | shares | 46,879,601 |  |  |
Business Acquisition, Share Price | $ / shares | $ 36.76 |  |  |
Core Deposits Intangibles |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Estimated useful lives of related deposits | 10 years | 10 years |  |

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- Definition Amount of currency on hand as well as demand deposits with banks or financial institutions, acquired at the acquisition date. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479907/805-20-50-1 + Details
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- Definition Amount of investments in debt and equity securities, including, but not limited to, held-to-maturity, trading and available-for-sale expected to be converted to cash, sold or exchanged within one year or the normal operating cycle, if longer, acquired at the acquisition date. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479907/805-20-50-1 + Details
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- Definition Amount of deferred tax asset attributable to deductible temporary differences and carryforwards acquired at the acquisition date. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479907/805-20-50-1 + Details
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