Fair Value Measurements (Estimated Fair Values of Financial Instruments) (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Held to maturity securities	$ 2,780,990	$ 2,852,495
Loans held for sale	24,163	10,843
Derivative assets	109,932	110,734
Derivative liabilities	111,599	32,601
Total Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash, interest-bearing bank deposits, and federal funds sold	1,237,899	888,519
Available for sale securities	5,414,689	5,556,041
Held to maturity securities	2,540,256	2,615,398
Loans, net	23,008,250	22,137,375
Loans held for sale	55,902	26,385
Derivative assets	108,474	109,497
Deposits	30,014,127	29,041,635
Federal funds purchased	400	1,850
Securities sold under agreements to repurchase	529,138	444,421
FHLB short-term borrowings	1,099,992	1,425,000
Long-term debt	195,972	200,060
Derivative liabilities	273,560	204,121
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	1,237,899	888,519
Federal funds purchased	400	1,850
Securities sold under agreements to repurchase	529,138	444,421
FHLB short-term borrowings		1,425,000
Total Fair Value [Member] | Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Available for sale securities	5,414,689	5,556,041
Held to maturity securities	2,540,256	2,615,398
Loans, net	37,507	4,692
Loans held for sale	55,902	26,385
Derivative assets	108,474	109,497
FHLB short-term borrowings	1,099,992
Long-term debt	195,972	200,060
Derivative liabilities	272,157	202,238
Total Fair Value [Member] | Level 3 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Loans, net	22,970,743	22,132,683
Deposits	30,014,127	29,041,635
Derivative liabilities	1,403	1,883
Carrying Amount [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash, interest-bearing bank deposits, and federal funds sold	1,237,899	888,519
Available for sale securities	5,414,689	5,556,041
Held to maturity securities	2,780,990	2,852,495
Loans, net	23,475,390	22,806,257
Loans held for sale	55,902	26,385
Derivative assets	108,474	109,497
Deposits	30,043,501	29,070,349
Federal funds purchased	400	1,850
Securities sold under agreements to repurchase	529,138	444,421
FHLB short-term borrowings	1,100,000	1,425,000
Long-term debt	236,241	242,077
Derivative liabilities	$ 273,560	$ 204,121