Fair Value Measurements (Estimated Fair Values of Financial Instruments) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Held to maturity securities	$ 2,653,759	$ 2,684,779
Loans held for sale	15,208	13,269
Derivative financial instruments, Financial assets	94,614	84,458
Derivative financial instruments, Financial liabilities	97,599	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	853,300	1,188,284
Available for sale securities	4,905,423	4,915,195
Held to maturity securities	2,436,610	2,485,918
Loans, net	23,156,551	23,186,259
Loans held for sale	16,470	26,124
Derivative financial instruments, Financial assets	94,689	90,712
Deposits	29,761,955	29,679,228
Federal funds purchased	350	350
Securities sold under agreements to repurchase	667,410	454,479
FHLB short-term borrowings		700,000
Long-term debt	191,331	196,182
Derivative financial instruments, Financial liabilities	235,380	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	853,300	1,188,284
Federal funds purchased	350	350
Securities sold under agreements to repurchase	667,410	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]
Available for sale securities	4,905,423	4,915,195
Held to maturity securities	2,436,610	2,485,918
Loans, net	37,176	15,882
Loans held for sale	16,470	26,124
Derivative financial instruments, Financial assets	94,689	90,712
Long-term debt	191,331	196,182
Derivative financial instruments, Financial liabilities	233,239	205,796
Total Fair Value [Member] | Level 3 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Loans, net	23,119,375	23,170,377
Deposits	29,761,955	29,679,228
Derivative financial instruments, Financial liabilities	2,141	1,342
Carrying Amount [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash, interest-bearing bank deposits, and federal funds sold	853,300	1,188,284
Available for sale securities	4,905,423	4,915,195
Held to maturity securities	2,653,759	2,684,779
Loans, net	23,657,212	23,614,010
Loans held for sale	16,470	26,124
Derivative financial instruments, Financial assets	94,689	90,712
Deposits	29,775,906	29,690,059
Federal funds purchased	350	350
Securities sold under agreements to repurchase	667,410	454,479
FHLB short-term borrowings		700,000
Long-term debt	236,355	236,317
Derivative financial instruments, Financial liabilities	$ 235,380	$ 207,138