Fair Value - Carrying Amounts and Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities held to maturity	$ 1,438,287	$ 1,494,514
Deposits	15,101,923	14,437,648
Federal funds purchased and securities sold under repurchase agreements	321,799	449,331
Other borrowings	793,193	1,050,938
Subordinated notes	123,427	123,262
Junior subordinated debt securities	61,856	61,856
Level 2 [Member] | Carrying Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and short-term investments	750,492	738,787
Securities held to maturity	1,438,287	1,494,514
Deposits	15,101,923	14,437,648
Federal funds purchased and securities sold under repurchase agreements	321,799	449,331
Other borrowings	793,193	1,050,938
Subordinated notes	123,427	123,262
Junior subordinated debt securities	61,856	61,856
Level 2 [Member] | Estimate Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and short-term investments	750,492	738,787
Securities held to maturity	1,312,871	1,406,589
Deposits	15,076,677	14,404,661
Federal funds purchased and securities sold under repurchase agreements	321,799	449,331
Other borrowings	793,188	1,050,932
Subordinated notes	103,750	113,125
Junior subordinated debt securities	45,928	46,392
Level 3 [Member] | Carrying Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net LHFI	12,676,228	12,083,825
Level 3 [Member] | Estimate Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net LHFI	$ 12,505,990	$ 11,850,318