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Loans Held for Investment - Schedule of Allowance for Credit Losses for Loans Held for Investment (Details) | 3 Months Ended | 6 Months Ended |
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Jun. 30, 2023 USD ($) Investments | Jun. 30, 2022 USD ($) | Jun. 30, 2023 USD ($) Investments | Jun. 30, 2022 USD ($) | Dec. 31, 2022 USD ($) Investments
Accounts Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Beginning balance | $ 226,100,000 | $ 247,200,000 | $ 220,100,000 | $ 122,300,000 |
Provision charged to operating expense | 11,700,000 | (1,700,000) | 26,900,000 | 59,600,000 |
Loans Charged-Off(2) | (14,100,000) | (3,700,000) | (23,000,000.0) | (23,600,000) |
Ending balance | 224,600,000 | 220,400,000 | 224,600,000 | 220,400,000 |
Provisional ACL Recorded for PCD loans |  | (24,800,000) |  | 59,500,000 |
Off-Balance Sheet, Credit Loss, Liability, Credit Loss Expense (Reversal) | 9,900,000 | (1,700,000) | 22,100,000 | 55,600,000 |
Financing Receivable, Allowance for Credit Loss, Recovery | 2,700,000 | 3,400,000 | 5,400,000 | 6,600,000 |
Interest Receivable | 119,100,000 |  | 119,100,000 |  | $ 118,300,000
Debt Securities, Available-for-sale, Realized Loss | $ 0 | 0 | $ (23,500,000) | 0 |
Allowance for Credit Losses |  |  |  |  | $ 0
Investment securities in an unrealized loss position (securities) | Investments | 1,030 |  | 1,030 |  | 1,222
Debt Securities, Available-for-sale, Realized Gain | $ 0 | 0 |  | 0 |
Securities Sold under Agreements to Repurchase, Fair Value of Collateral | 7,227,800,000 |  | $ 7,227,800,000 |  | $ 4,998,900,000
Securities Loaned or Sold under Agreements to Repurchase, Fair Value Disclosure | 6,455,100,000 |  | 6,455,100,000 |  | 4,432,000,000
Callable Within One Year |  |  |  |  |
Accounts Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Amortized cost of investment securities callable after one year but within five years | 1,593,800,000 |  | 1,593,800,000 |  |
Fair value of investment securities callable after one year but within five years | 1,521,200,000 |  | 1,521,200,000 |  |
Callable structured notes amortized costs | 0 |  | 0 |  |
Debt Securities |  |  |  |  |
Accounts Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Interest Receivable | 38,100,000 |  | 38,100,000 |  | $ 38,900,000
Commercial Real Estate Non Owner Occupied Loans [Member] |  |  |  |  |
Accounts Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Beginning balance |  | 45,200,000 |  | 17,300,000 |
Provision charged to operating expense |  | (8,800,000) |  | (2,100,000) |
Loans Charged-Off(2) |  | 0 |  | (2,900,000) |
Ending balance |  | 29,500,000 |  | 29,500,000 |
Provisional ACL Recorded for PCD loans |  | (6,900,000) |  | 17,200,000 |
Financing Receivable, Allowance for Credit Loss, Recovery |  | 0 |  | 0 |
Agricultural Financing Receivable [Member] |  |  |  |  |
Accounts Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Beginning balance | 2,400,000 | (1,000,000.0) | 3,200,000 | 300,000 |
Provision charged to operating expense | 200,000 | 6,300,000 | (900,000) | 5,800,000 |
Loans Charged-Off(2) | 0 | (100,000) | 0 | (5,400,000) |
Ending balance | 2,700,000 | 6,500,000 | 2,700,000 | 6,500,000 |
Provisional ACL Recorded for PCD loans |  | 1,100,000 |  | 4,500,000 |
Financing Receivable, Allowance for Credit Loss, Recovery | 100,000 | 200,000 | 400,000 | 1,300,000 |
Commercial and Floor Plans [Member] |  |  |  |  |
Accounts Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Beginning balance |  | 52,900,000 |  | 27,100,000 |
Provision charged to operating expense |  | 1,900,000 |  | 20,300,000 |
Loans Charged-Off(2) |  | (1,100,000) |  | (5,300,000) |
Ending balance |  | 54,100,000 |  | 54,100,000 |
Provisional ACL Recorded for PCD loans |  | 0 |  | 11,200,000 |
Financing Receivable, Allowance for Credit Loss, Recovery |  | 400,000 |  | 800,000 |
Commercial Real Estate Owner Occupied [Member] |  |  |  |  |
Accounts Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Beginning balance |  | 25,200,000 |  | 13,300,000 |
Provision charged to operating expense |  | 1,400,000 |  | 6,000,000.0 |
Loans Charged-Off(2) |  | 0 |  | (2,200,000) |
Ending balance |  | 26,600,000 |  | 26,600,000 |
Provisional ACL Recorded for PCD loans |  | 0 |  | 9,500,000 |
Financing Receivable, Allowance for Credit Loss, Recovery |  | 0 |  | 0 |
Commercial Real Estate Multi-family [Member] |  |  |  |  |
Accounts Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Beginning balance |  | 54,600,000 |  | 13,300,000 |
Provision charged to operating expense |  | (2,900,000) |  | 8,500,000 |
Loans Charged-Off(2) |  | 0 |  | 0 |
Ending balance |  | 33,400,000 |  | 33,400,000 |
Provisional ACL Recorded for PCD loans |  | (19,000,000.0) |  | 10,900,000 |
Financing Receivable, Allowance for Credit Loss, Recovery |  | 700,000 |  | 700,000 |
Commercial real estate |  |  |  |  |
Accounts Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Beginning balance |  | 125,000,000.0 |  | 43,900,000 |
Provision charged to operating expense |  | (10,300,000) |  | 12,400,000 |
Loans Charged-Off(2) |  | 0 | (4,600,000) | (5,100,000) |
Ending balance |  | 89,500,000 |  | 89,500,000 |
Provisional ACL Recorded for PCD loans |  | (25,900,000) |  | 37,600,000 |
Financing Receivable, Allowance for Credit Loss, Recovery |  | 700,000 |  | 700,000 |
Land Acquisition And Development Construction Financing Receivable [Member] |  |  |  |  |
Accounts Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Beginning balance |  | 500,000 |  | 500,000 |
Provision charged to operating expense |  | 200,000 |  | (600,000) |
Loans Charged-Off(2) |  | 0 |  | (2,700,000) |
Ending balance |  | 800,000 |  | 800,000 |
Provisional ACL Recorded for PCD loans |  | 0 |  | 3,400,000 |
Financing Receivable, Allowance for Credit Loss, Recovery |  | 100,000 |  | 200,000 |
Residential construction |  |  |  |  |
Accounts Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Beginning balance |  | 3,300,000 |  | 2,400,000 |
Provision charged to operating expense |  | 100,000 |  | 1,000,000.0 |
Loans Charged-Off(2) |  | 0 |  | 0 |
Ending balance |  | 3,400,000 |  | 3,400,000 |
Provisional ACL Recorded for PCD loans |  | 0 |  | 0 |
Financing Receivable, Allowance for Credit Loss, Recovery |  | 0 |  | 0 |
Commercial construction |  |  |  |  |
Accounts Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Beginning balance |  | 10,200,000 |  | 6,000,000.0 |
Provision charged to operating expense |  | 4,700,000 |  | 8,700,000 |
Loans Charged-Off(2) |  | 0 |  | 0 |
Ending balance |  | 14,900,000 |  | 14,900,000 |
Provisional ACL Recorded for PCD loans |  | 0 |  | 200,000 |
Financing Receivable, Allowance for Credit Loss, Recovery |  | 0 |  | 0 |
Construction Loans [Member] |  |  |  |  |
Accounts Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Beginning balance |  | 14,000,000.0 |  | 8,900,000 |
Provision charged to operating expense |  | 5,000,000.0 |  | 9,100,000 |
Loans Charged-Off(2) |  | 0 |  | (2,700,000) |
Ending balance |  | 19,100,000 |  | 19,100,000 |
Provisional ACL Recorded for PCD loans |  | 0 |  | 3,600,000 |
Financing Receivable, Allowance for Credit Loss, Recovery |  | 100,000 |  | 200,000 |
Residential Real Estate 1-4 Family [Member] |  |  |  |  |
Accounts Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Beginning balance |  | 18,700,000 |  | 13,400,000 |
Provision charged to operating expense |  | (700,000) |  | 4,500,000 |
Loans Charged-Off(2) |  | 0 |  | (100,000) |
Ending balance |  | 18,200,000 |  | 18,200,000 |
Provisional ACL Recorded for PCD loans |  | 0 |  | 100,000 |
Financing Receivable, Allowance for Credit Loss, Recovery |  | 200,000 |  | 300,000 |
Home Equity Line of Credit [Member] |  |  |  |  |
Accounts Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Beginning balance |  | 1,400,000 |  | 1,200,000 |
Provision charged to operating expense |  | (100,000) |  | 0 |
Loans Charged-Off(2) |  | 0 |  | 0 |
Ending balance |  | 1,500,000 |  | 1,500,000 |
Provisional ACL Recorded for PCD loans |  | 0 |  | 0 |
Financing Receivable, Allowance for Credit Loss, Recovery |  | 200,000 |  | 300,000 |
Residential Real Estate [Member] |  |  |  |  |
Accounts Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Beginning balance |  | 20,100,000 |  | 14,600,000 |
Provision charged to operating expense |  | (800,000) |  | 4,500,000 |
Loans Charged-Off(2) |  | 0 | (500,000) | (100,000) |
Ending balance |  | 19,700,000 |  | 19,700,000 |
Provisional ACL Recorded for PCD loans |  | 0 |  | 100,000 |
Financing Receivable, Allowance for Credit Loss, Recovery |  | 400,000 |  | 600,000 |
Agricultural Real Estate Financing Receivable [Member] |  |  |  |  |
Accounts Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Beginning balance |  | 10,500,000 |  | 1,900,000 |
Provision charged to operating expense |  | (5,100,000) |  | 1,300,000 |
Loans Charged-Off(2) |  | (100,000) | 0 | (200,000) |
Ending balance |  | 5,400,000 |  | 5,400,000 |
Provisional ACL Recorded for PCD loans |  | 0 |  | 2,300,000 |
Financing Receivable, Allowance for Credit Loss, Recovery |  | 100,000 |  | 100,000 |
Real Estate Financing Receivable [Member] |  |  |  |  |
Accounts Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Beginning balance | 147,500,000 | 169,600,000 | 138,700,000 | 69,300,000 |
Provision charged to operating expense | 20,400,000 | (11,200,000) | 33,800,000 | 27,300,000 |
Loans Charged-Off(2) | (10,000,000.0) | (100,000) | (14,800,000) | (8,100,000) |
Ending balance | 158,700,000 | 133,700,000 | 158,700,000 | 133,700,000 |
Provisional ACL Recorded for PCD loans |  | (25,900,000) |  | 43,600,000 |
Financing Receivable, Allowance for Credit Loss, Recovery | 800,000 | 1,300,000 | 1,000,000.0 | 1,600,000 |
Consumer Indirect Financing Receivable [Member] |  |  |  |  |
Accounts Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Beginning balance |  | 13,500,000 |  | 14,300,000 |
Provision charged to operating expense |  | (400,000) |  | (700,000) |
Loans Charged-Off(2) |  | (800,000) | (3,400,000) | (1,700,000) |
Ending balance |  | 13,100,000 |  | 13,100,000 |
Provisional ACL Recorded for PCD loans |  | 0 |  | 0 |
Financing Receivable, Allowance for Credit Loss, Recovery |  | 800,000 |  | 1,200,000 |
Direct consumer |  |  |  |  |
Accounts Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Beginning balance |  | 4,600,000 |  | 4,600,000 |
Provision charged to operating expense |  | 500,000 |  | 400,000 |
Loans Charged-Off(2) |  | (600,000) | (1,900,000) | (1,400,000) |
Ending balance |  | 5,000,000.0 |  | 5,000,000.0 |
Provisional ACL Recorded for PCD loans |  | 0 |  | 0 |
Financing Receivable, Allowance for Credit Loss, Recovery |  | 500,000 |  | 1,400,000 |
Credit Card Receivable [Member] |  |  |  |  |
Accounts Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Beginning balance |  | 2,300,000 |  | 2,200,000 |
Provision charged to operating expense |  | 700,000 |  | 1,300,000 |
Loans Charged-Off(2) |  | (900,000) | (1,400,000) | (1,500,000) |
Ending balance |  | 2,200,000 |  | 2,200,000 |
Provisional ACL Recorded for PCD loans |  | 0 |  | 0 |
Financing Receivable, Allowance for Credit Loss, Recovery |  | 100,000 |  | 200,000 |
Consumer |  |  |  |  |
Accounts Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Beginning balance | 21,800,000 | 20,400,000 | 23,300,000 | 21,100,000 |
Provision charged to operating expense | (6,200,000) | 800,000 | (5,500,000) | 1,000,000.0 |
Loans Charged-Off(2) | (3,300,000) | (2,300,000) | (6,700,000) | (4,600,000) |
Ending balance | 13,700,000 | 20,300,000 | 13,700,000 | 20,300,000 |
Provisional ACL Recorded for PCD loans |  | 0 |  | 0 |
Financing Receivable, Allowance for Credit Loss, Recovery | 1,400,000 | 1,400,000 | 2,600,000 | 2,800,000 |
Commercial Purpose secured by 1-4 Family [Member] |  |  |  |  |
Accounts Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Beginning balance |  | 5,000,000.0 |  | 4,400,000 |
Provision charged to operating expense |  | 400,000 |  | 800,000 |
Loans Charged-Off(2) |  | 0 |  | 0 |
Ending balance |  | 5,500,000 |  | 5,500,000 |
Provisional ACL Recorded for PCD loans |  | 0 |  | 200,000 |
Financing Receivable, Allowance for Credit Loss, Recovery |  | 100,000 |  | 100,000 |
Commercial Borrower [Member] |  |  |  |  |
Accounts Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Beginning balance |  | 300,000 |  | 100,000 |
Provision charged to operating expense |  | 100,000 |  | 400,000 |
Loans Charged-Off(2) |  | (100,000) |  | (200,000) |
Ending balance |  | 300,000 |  | 300,000 |
Provisional ACL Recorded for PCD loans |  | 0 |  | 0 |
Financing Receivable, Allowance for Credit Loss, Recovery |  | 0 |  | 0 |
Commercial Portfolio Segment [Member] |  |  |  |  |
Accounts Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Beginning balance | 54,400,000 | 58,200,000 | 54,900,000 | 31,600,000 |
Provision charged to operating expense | (4,500,000) | 2,400,000 | (5,300,000) | 21,500,000 |
Loans Charged-Off(2) | (800,000) | (1,200,000) | (1,500,000) | (5,500,000) |
Ending balance | 49,500,000 | 59,900,000 | 49,500,000 | 59,900,000 |
Provisional ACL Recorded for PCD loans |  | 0 |  | 11,400,000 |
Financing Receivable, Allowance for Credit Loss, Recovery | $ 400,000 | $ 500,000 | $ 1,400,000 | $ 900,000 |

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- Definition Available-for-Sale and Held-to-Maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions + References No definition available. + Details
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- Definition Amount of allowance for credit loss on accounts receivable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (a) -URI https://asc.fasb.org/extlink&oid=124255953&loc=SL82919249-210447 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 4 -URI https://asc.fasb.org/extlink&oid=123577603&loc=d3e5074-111524 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (f) -URI https://asc.fasb.org/extlink&oid=124255953&loc=SL82919249-210447 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 45 -Paragraph 1 -URI https://asc.fasb.org/extlink&oid=124255206&loc=SL82895884-210446 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(4)) -URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
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