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Fair Value Measurements - Schedule of Estimated Fair Values of Financial Instruments by Level of Valuation Inputs (Details) - USD ($) $ in Millions | Mar. 31, 2023 | Dec. 31, 2022
--- | --- | ---
Financial assets: |  |
Investment debt securities held-to-maturity | $ 3,025.8 | $ 3,052.2
Derivative assets | 43.1 | 45.2
Financial liabilities: |  |
Derivative liabilities | 126.7 | 159.6
Estimated Fair Value |  |
Financial assets: |  |
Cash and cash equivalents | 1,080.7 | 870.5
Investment debt securities available-for-sale | 6,049.3 | 6,946.1
Investment debt securities held-to-maturity | 3,025.8 | 3,052.2
Accrued interest receivable | 113.7 | 118.3
Mortgage servicing rights, net | 38.1 | 37.4
Loans held for sale | 80.9 | 79.9
Net loans held for investment | 17,585.5 | 17,552.1
Derivative assets | 43.1 | 45.2
Deferred compensation plan assets | 17.3 | 18.7
Total financial assets | 28,034.4 | 28,720.4
Financial liabilities: |  |
Total deposits, excluding time deposits | 21,858.1 | 23,145.2
Time deposits | 2,198.8 | 1,876.1
Securities sold under repurchase agreements | 970.8 | 1,052.9
Other Borrowings | 2,710.0 | 2,327.0
Accrued interest payable | 26.1 | 14.5
Long-term debt | 114.5 | 116.3
Subordinated debentures held by subsidiary trusts | 157.8 | 155.8
Derivative liabilities | 126.7 | 159.6
Deferred compensation plan liabilities | 17.3 | 18.7
Total financial liabilities | 28,180.1 | 28,866.1
Carrying Amount |  |
Financial assets: |  |
Cash and cash equivalents | 1,080.7 | 870.5
Investment debt securities available-for-sale | 6,049.3 | 6,946.1
Investment debt securities held-to-maturity | 3,376.2 | 3,451.8
Accrued interest receivable | 113.7 | 118.3
Mortgage servicing rights, net | 30.1 | 31.1
Loans held for sale | 80.9 | 79.9
Net loans held for investment | 18,019.6 | 17,879.1
Derivative assets | 43.1 | 45.2
Deferred compensation plan assets | 17.3 | 18.7
Total financial assets | 28,810.9 | 29,440.7
Financial liabilities: |  |
Total deposits, excluding time deposits | 21,858.1 | 23,145.2
Time deposits | 2,248.9 | 1,928.4
Securities sold under repurchase agreements | 970.8 | 1,052.9
Other Borrowings | 2,710.0 | 2,327.0
Accrued interest payable | 26.1 | 14.5
Long-term debt | 120.8 | 120.8
Subordinated debentures held by subsidiary trusts | 163.1 | 163.1
Derivative liabilities | 126.7 | 159.6
Deferred compensation plan liabilities | 17.3 | 18.7
Total financial liabilities | 28,241.8 | 28,930.2
Quoted Prices in Active Markets for Identical Assets (Level 1) | Estimated Fair Value |  |
Financial assets: |  |
Cash and cash equivalents | 1,080.7 | 870.5
Investment debt securities available-for-sale | 0.0 | 0.0
Investment debt securities held-to-maturity | 0.0 | 0.0
Accrued interest receivable | 0.0 | 0.0
Mortgage servicing rights, net | 0.0 | 0.0
Loans held for sale | 0.0 | 0.0
Net loans held for investment | 0.0 | 0.0
Derivative assets | 0.0 | 0.0
Deferred compensation plan assets | 0.0 | 0.0
Total financial assets | 1,080.7 | 870.5
Financial liabilities: |  |
Total deposits, excluding time deposits | 21,858.1 | 23,145.2
Time deposits | 0.0 | 0.0
Securities sold under repurchase agreements | 0.0 | 0.0
Other Borrowings | 0.0 | 0.0
Accrued interest payable | 0.0 | 0.0
Long-term debt | 0.0 | 0.0
Subordinated debentures held by subsidiary trusts | 0.0 | 0.0
Derivative liabilities | 0.0 | 0.0
Deferred compensation plan liabilities | 0.0 | 0.0
Total financial liabilities | 21,858.1 | 23,145.2
Significant Other Observable Inputs (Level 2) | Estimated Fair Value |  |
Financial assets: |  |
Cash and cash equivalents | 0.0 | 0.0
Investment debt securities available-for-sale | 6,049.3 | 6,946.1
Investment debt securities held-to-maturity | 3,025.8 | 3,052.2
Accrued interest receivable | 113.7 | 118.3
Mortgage servicing rights, net | 38.1 | 37.4
Loans held for sale | 8.5 | 6.9
Net loans held for investment | 17,526.0 | 17,513.0
Derivative assets | 43.1 | 45.2
Deferred compensation plan assets | 17.3 | 18.7
Total financial assets | 26,821.8 | 27,737.8
Financial liabilities: |  |
Total deposits, excluding time deposits | 0.0 | 0.0
Time deposits | 2,198.8 | 1,876.1
Securities sold under repurchase agreements | 970.8 | 1,052.9
Other Borrowings | 2,710.0 | 2,327.0
Accrued interest payable | 26.1 | 14.5
Long-term debt | 114.5 | 116.3
Subordinated debentures held by subsidiary trusts | 157.8 | 155.8
Derivative liabilities | 126.7 | 159.6
Deferred compensation plan liabilities | 17.3 | 18.7
Total financial liabilities | 6,322.0 | 5,720.9
Significant Unobservable Inputs (Level 3) | Estimated Fair Value |  |
Financial assets: |  |
Cash and cash equivalents | 0.0 | 0.0
Investment debt securities available-for-sale | 0.0 | 0.0
Investment debt securities held-to-maturity | 0.0 | 0.0
Accrued interest receivable | 0.0 | 0.0
Mortgage servicing rights, net | 0.0 | 0.0
Loans held for sale | 72.4 | 73.0
Net loans held for investment | 59.5 | 39.1
Derivative assets | 0.0 | 0.0
Deferred compensation plan assets | 0.0 | 0.0
Total financial assets | 131.9 | 112.1
Financial liabilities: |  |
Total deposits, excluding time deposits | 0.0 | 0.0
Time deposits | 0.0 | 0.0
Securities sold under repurchase agreements | 0.0 | 0.0
Other Borrowings | 0.0 | 0.0
Accrued interest payable | 0.0 | 0.0
Long-term debt | 0.0 | 0.0
Subordinated debentures held by subsidiary trusts | 0.0 | 0.0
Derivative liabilities | 0.0 | 0.0
Deferred compensation plan liabilities | 0.0 | 0.0
Total financial liabilities | $ 0.0 | $ 0.0

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