Mortgage Banking Activities, Mortgage Servicing Rights (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)
Summary of Mortgage Servicing Rights [Abstract]
Number of residential mortgage loans serviced for others	122,276		115,967
Outstanding principal balance of residential mortgage loans serviced for others	$ 21,432,048,000		$ 20,382,192,000
Weighted average interest rate	3.66%		3.64%
Remaining term (in months)	278 months		280 months
Servicing Asset at Fair Value, Amount [Roll Forward]
Beginning balance	$ 293,884,000	$ 277,608,000	$ 277,608,000
Additions	2,516,000	2,500,000
Acquisitions	17,400,000	31,138,000
Changes due to principal payments	(5,447,000)	(5,384,000)
Change in fair value due to market assumption changes	10,977,000	(6,059,000)
Ending balance	$ 319,330,000	$ 299,803,000	$ 293,884,000
Servicing Assets at Fair Value, Assumptions Used to Estimate Fair Value [Abstract]
Discount rate - risk-free rate plus a market premium (in hundredths)	9.82%		9.72%
Prepayment rate - based upon loan interest rate, original term and loan type	6.83%		7.34%
Loan servicing costs - annually per loan based upon loan type, performing, minimum (in dollars per loan)	$ 73		$ 69
Loan servicing costs - annually per loan based upon loan type, performing, maximum (in dollars per loan)	94		94
Loan servicing costs - annually per loan based upon loan type, delinquent, minimum (in dollars per loan)	150		150
Loan servicing costs - annually per loan based upon loan type, delinquent, maximum (in dollars per loan)	500		500
Loan servicing costs - annually per loan based upon loan type, foreclosure, minimum (in dollars per loan)	875		875
Loan servicing costs - annually per loan based upon loan type, foreclosure, maximum (in dollars per loan)	$ 8,000		$ 8,000
Escrow earnings rate - indexed to rates paid on deposit accounts with comparable average life (in hundredths)	4.27%		3.90%
Primary secondary mortgage rate spread	115		105
Delinquency rate	2.06%		2.06%