Loans Held for Investment - Schedule of Allowance for Credit Losses for Loans Held for Investment (Details)		3 Months Ended
	Mar. 13, 2023 USD ($)	Mar. 31, 2023 USD ($) Investments	Mar. 31, 2022 USD ($)	Dec. 31, 2022 USD ($) Investments
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		$ 220,100,000	$ 122,300,000
Provision charged to operating expense		15,200,000	61,300,000
Loans Charged-Off(2)		(8,900,000)	(19,900,000)
Ending balance		226,100,000	247,200,000
Provisional ACL Recorded for PCD loans			84,300,000
Off-Balance Sheet, Credit Loss, Liability, Credit Loss Expense (Reversal)		12,200,000	57,300,000
Financing Receivable, Allowance for Credit Loss, Recovery		2,700,000	3,200,000
Interest Receivable		113,700,000		$ 118,300,000
Debt Securities, Available-for-sale, Realized Loss		$ (23,400,000)	0
Debt Securities, Held-To-Maturity, After Allowance For Credit Loss, Transfer, Amount	$ 13,200,000
Allowance for Credit Losses	800,000			$ 0
Investment securities in an unrealized loss position (securities) | Investments		1,023		1,222
Debt Securities, Available-for-sale, Realized Gain		$ 0	0
Securities Sold under Agreements to Repurchase, Fair Value of Collateral		3,607,300,000		$ 4,998,900,000
Securities Loaned or Sold under Agreements to Repurchase, Fair Value Disclosure		3,228,500,000		4,432,000,000
Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss, Transfer, Amount	$ 23,000,000
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		1,525,900,000
Fair value of investment securities callable after one year but within five years		1,446,900,000
Callable structured notes amortized costs		0
Debt Securities
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Interest Receivable		35,600,000		$ 38,900,000
Commercial Real Estate Non Owner Occupied Loans [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		27,200,000	17,300,000
Provision charged to operating expense		1,300,000	6,700,000
Loans Charged-Off(2)		(2,500,000)	(2,900,000)
Ending balance		26,000,000.0	45,200,000
Provisional ACL Recorded for PCD loans			24,100,000
Financing Receivable, Allowance for Credit Loss, Recovery		0	0
Agricultural Financing Receivable [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		3,200,000	300,000
Provision charged to operating expense		(1,100,000)	(500,000)
Loans Charged-Off(2)		0	(5,300,000)
Ending balance		2,400,000	(1,000,000.0)
Provisional ACL Recorded for PCD loans			3,400,000
Financing Receivable, Allowance for Credit Loss, Recovery		300,000	1,100,000
Commercial and Floor Plans [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		49,000,000.0	27,100,000
Provision charged to operating expense		(800,000)	18,400,000
Loans Charged-Off(2)		(600,000)	(4,200,000)
Ending balance		48,500,000	52,900,000
Provisional ACL Recorded for PCD loans			11,200,000
Financing Receivable, Allowance for Credit Loss, Recovery		900,000	400,000
Commercial Real Estate Owner Occupied [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		19,500,000	13,300,000
Provision charged to operating expense		(200,000)	4,600,000
Loans Charged-Off(2)		(1,800,000)	(2,200,000)
Ending balance		17,600,000	25,200,000
Provisional ACL Recorded for PCD loans			9,500,000
Financing Receivable, Allowance for Credit Loss, Recovery		100,000	0
Commercial Real Estate Multi-family [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		27,900,000	13,300,000
Provision charged to operating expense		7,100,000	11,400,000
Loans Charged-Off(2)		0	0
Ending balance		35,000,000.0	54,600,000
Provisional ACL Recorded for PCD loans			29,900,000
Financing Receivable, Allowance for Credit Loss, Recovery		0	0
Commercial real estate
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		74,600,000	43,900,000
Provision charged to operating expense		8,200,000	22,700,000
Loans Charged-Off(2)		(4,300,000)	(5,100,000)
Ending balance		78,600,000	125,000,000.0
Provisional ACL Recorded for PCD loans			63,500,000
Financing Receivable, Allowance for Credit Loss, Recovery		100,000	0
Land Acquisition And Development Construction Financing Receivable [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		1,300,000	500,000
Provision charged to operating expense		300,000	(800,000)
Loans Charged-Off(2)		0	(2,700,000)
Ending balance		1,600,000	500,000
Provisional ACL Recorded for PCD loans			3,400,000
Financing Receivable, Allowance for Credit Loss, Recovery		0	100,000
Residential construction
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		3,600,000	2,400,000
Provision charged to operating expense		100,000	900,000
Loans Charged-Off(2)		0	0
Ending balance		3,700,000	3,300,000
Provisional ACL Recorded for PCD loans			0
Financing Receivable, Allowance for Credit Loss, Recovery		0	0
Commercial construction
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		31,200,000	6,000,000.0
Provision charged to operating expense		5,900,000	4,000,000.0
Loans Charged-Off(2)		0	0
Ending balance		37,100,000	10,200,000
Provisional ACL Recorded for PCD loans			200,000
Financing Receivable, Allowance for Credit Loss, Recovery		0	0
Construction Loans [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		36,100,000	8,900,000
Provision charged to operating expense		6,300,000	4,100,000
Loans Charged-Off(2)		0	(2,700,000)
Ending balance		42,400,000	14,000,000.0
Provisional ACL Recorded for PCD loans			3,600,000
Financing Receivable, Allowance for Credit Loss, Recovery		0	100,000
Residential Real Estate 1-4 Family [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		20,500,000	13,400,000
Provision charged to operating expense		(200,000)	5,200,000
Loans Charged-Off(2)		(100,000)	(100,000)
Ending balance		20,200,000	18,700,000
Provisional ACL Recorded for PCD loans			100,000
Financing Receivable, Allowance for Credit Loss, Recovery		0	100,000
Home Equity Line of Credit [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		1,600,000	1,200,000
Provision charged to operating expense		300,000	100,000
Loans Charged-Off(2)		(400,000)	0
Ending balance		1,500,000	1,400,000
Provisional ACL Recorded for PCD loans			0
Financing Receivable, Allowance for Credit Loss, Recovery		0	100,000
Residential Real Estate [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		22,100,000	14,600,000
Provision charged to operating expense		100,000	5,300,000
Loans Charged-Off(2)		(500,000)	(100,000)
Ending balance		21,700,000	20,100,000
Provisional ACL Recorded for PCD loans			100,000
Financing Receivable, Allowance for Credit Loss, Recovery		0	200,000
Agricultural Real Estate Financing Receivable [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		5,900,000	1,900,000
Provision charged to operating expense		(1,200,000)	6,400,000
Loans Charged-Off(2)		0	(100,000)
Ending balance		4,800,000	10,500,000
Provisional ACL Recorded for PCD loans			2,300,000
Financing Receivable, Allowance for Credit Loss, Recovery		100,000	0
Real Estate Financing Receivable [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		138,700,000	69,300,000
Provision charged to operating expense		13,400,000	38,500,000
Loans Charged-Off(2)		(4,800,000)	(8,000,000.0)
Ending balance		147,500,000	169,600,000
Provisional ACL Recorded for PCD loans			69,500,000
Financing Receivable, Allowance for Credit Loss, Recovery		200,000	300,000
Consumer Indirect Financing Receivable [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		15,300,000	14,300,000
Provision charged to operating expense		600,000	(300,000)
Loans Charged-Off(2)		(1,800,000)	(900,000)
Ending balance		14,800,000	13,500,000
Provisional ACL Recorded for PCD loans			0
Financing Receivable, Allowance for Credit Loss, Recovery		700,000	400,000
Direct consumer
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		5,200,000	4,600,000
Provision charged to operating expense		100,000	(100,000)
Loans Charged-Off(2)		(1,100,000)	(800,000)
Ending balance		4,500,000	4,600,000
Provisional ACL Recorded for PCD loans			0
Financing Receivable, Allowance for Credit Loss, Recovery		300,000	900,000
Credit Card Receivable [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		2,800,000	2,200,000
Provision charged to operating expense		0	600,000
Loans Charged-Off(2)		(500,000)	(600,000)
Ending balance		2,500,000	2,300,000
Provisional ACL Recorded for PCD loans			0
Financing Receivable, Allowance for Credit Loss, Recovery		200,000	100,000
Consumer
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		23,300,000	21,100,000
Provision charged to operating expense		700,000	200,000
Loans Charged-Off(2)		(3,400,000)	(2,300,000)
Ending balance		21,800,000	20,400,000
Provisional ACL Recorded for PCD loans			0
Financing Receivable, Allowance for Credit Loss, Recovery		1,200,000	1,400,000
Commercial Purpose secured by 1-4 Family [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		5,700,000	4,400,000
Provision charged to operating expense		(200,000)	400,000
Loans Charged-Off(2)		0	0
Ending balance		5,600,000	5,000,000.0
Provisional ACL Recorded for PCD loans			200,000
Financing Receivable, Allowance for Credit Loss, Recovery		100,000	0
Commercial Borrower [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		200,000	100,000
Provision charged to operating expense		200,000	300,000
Loans Charged-Off(2)		(100,000)	(100,000)
Ending balance		300,000	300,000
Provisional ACL Recorded for PCD loans			0
Financing Receivable, Allowance for Credit Loss, Recovery		0	0
Commercial Portfolio Segment [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		54,900,000	31,600,000
Provision charged to operating expense		(800,000)	19,100,000
Loans Charged-Off(2)		(700,000)	(4,300,000)
Ending balance		54,400,000	58,200,000
Provisional ACL Recorded for PCD loans			11,400,000
Financing Receivable, Allowance for Credit Loss, Recovery		$ 1,000,000.0	400,000
Agriculture Portfolio Segment [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Provisional ACL Recorded for PCD loans			$ 3,400,000