Fair Value Measurements (Estimated Fair Values of Financial Instruments) (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Held to maturity securities	$ 2,197,611	$ 2,435,663
Loans held for sale	33,161	18,929
Derivative financial instruments, Financial assets	49,736	71,893
Derivative financial instruments, Financial liabilities	42,453	54,707
Total Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash, interest-bearing bank deposits, and federal funds sold	1,425,896	1,514,625
Available for sale securities	5,793,670	5,161,491
Held to maturity securities	2,064,591	2,233,526
Loans, net	23,186,462	22,562,577
Loans held for sale	33,161	21,525
Derivative financial instruments, Financial assets	68,156	73,840
Deposits	28,653,441	29,482,628
Federal funds purchased	300	300
Securities sold under agreements to repurchase	616,220	638,715
FHLB short-term borrowings	1,275,047
Long-term debt	176,174	174,660
Derivative financial instruments, Financial liabilities	106,582	160,623
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	1,425,650	1,514,216
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	246	409
Available for sale securities	5,793,670	5,161,491
Held to maturity securities	2,064,591	2,233,526
Loans held for sale	33,161	21,525
Derivative financial instruments, Financial assets	68,156	73,840
Federal funds purchased	300	300
Securities sold under agreements to repurchase	616,220	638,715
FHLB short-term borrowings	1,275,047
Long-term debt	176,174	174,660
Derivative financial instruments, Financial liabilities	104,727	158,534
Total Fair Value [Member] | Level 3 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Loans, net	23,186,462	22,562,577
Deposits	28,653,441	29,482,628
Derivative financial instruments, Financial liabilities	1,855	2,089
Carrying Amount [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash, interest-bearing bank deposits, and federal funds sold	1,425,896	1,514,625
Available for sale securities	5,793,670	5,161,491
Held to maturity securities	2,197,611	2,435,663
Loans, net	23,282,929	22,980,565
Loans held for sale	33,161	21,525
Derivative financial instruments, Financial assets	68,156	73,840
Deposits	28,659,750	29,492,851
Federal funds purchased	300	300
Securities sold under agreements to repurchase	616,220	638,715
FHLB short-term borrowings	1,275,000
Long-term debt	210,657	210,544
Derivative financial instruments, Financial liabilities	$ 106,582	$ 160,623