Fair Value Measurements (Estimated Fair Values of Financial Instruments) (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Held to maturity securities	$ 2,473,633	$ 2,684,779
Loans held for sale	23,462	13,269
Derivative financial instruments, Financial assets	55,440	84,458
Derivative financial instruments, Financial liabilities	52,690	87,567
Total Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash, interest-bearing bank deposits, and federal funds sold	1,365,107	1,188,284
Available for sale securities	5,296,147	4,915,195
Held to maturity securities	2,325,258	2,485,918
Loans, net	22,908,761	23,186,259
Loans held for sale	24,624	26,124
Derivative financial instruments, Financial assets	69,815	90,712
Deposits	28,978,151	29,679,228
Federal funds purchased	200,275	350
Securities sold under agreements to repurchase	765,669	454,479
FHLB short-term borrowings	300,000	700,000
Long-term debt	202,109	196,182
Derivative financial instruments, Financial liabilities	132,029	207,138
Total Fair Value [Member] | Level 1 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash, interest-bearing bank deposits, and federal funds sold	1,364,683	1,188,284
Federal funds purchased		350
Securities sold under agreements to repurchase		454,479
FHLB short-term borrowings		700,000
Total Fair Value [Member] | Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash, interest-bearing bank deposits, and federal funds sold	424
Available for sale securities	5,296,147	4,915,195
Held to maturity securities	2,325,258	2,485,918
Loans, net	26,016	15,882
Loans held for sale	24,624	26,124
Derivative financial instruments, Financial assets	69,815	90,712
Federal funds purchased	200,275
Securities sold under agreements to repurchase	765,669
FHLB short-term borrowings	300,000
Long-term debt	202,109	196,182
Derivative financial instruments, Financial liabilities	129,768	205,796
Total Fair Value [Member] | Level 3 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Loans, net	22,882,745	23,170,377
Deposits	28,978,151	29,679,228
Derivative financial instruments, Financial liabilities	2,261	1,342
Carrying Amount [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash, interest-bearing bank deposits, and federal funds sold	1,365,107	1,188,284
Available for sale securities	5,296,147	4,915,195
Held to maturity securities	2,473,633	2,684,779
Loans, net	23,138,316	23,614,010
Loans held for sale	24,624	26,124
Derivative financial instruments, Financial assets	69,815	90,712
Deposits	28,982,905	29,690,059
Federal funds purchased	200,275	350
Securities sold under agreements to repurchase	765,669	454,479
FHLB short-term borrowings	300,000	700,000
Long-term debt	236,431	236,317
Derivative financial instruments, Financial liabilities	$ 132,029	$ 207,138