Short-Term Borrowings (Short-Term Borrowings) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Short-Term Debt [Line Items]
Amount outstanding at period end	$ 1,425,928		$ 1,425,928		$ 1,871,271
Federal Funds Purchased [Member]
Short-Term Debt [Line Items]
Amount outstanding at period end	$ 350		$ 350		$ 1,850
Weighted-average interest at period end	4.90%		4.90%		3.90%
Average amount outstanding during period	$ 7,665	$ 28,861	$ 5,785	$ 11,425
Maximum amount at any month end during period	$ 350	$ 1,850	$ 1,850	$ 2,350
Weighted-average interest rate during period	6.16%	2.59%	5.58%	2.29%
Securities Sold under Agreements to Repurchase [Member]
Short-Term Debt [Line Items]
Amount outstanding at period end	$ 525,578		$ 525,578		$ 444,421
Weighted-average interest at period end	1.46%		1.46%		0.53%
Average amount outstanding during period	$ 538,167	$ 516,546	$ 494,298	$ 542,105
Maximum amount at any month end during period	$ 525,578	$ 541,131	$ 625,773	$ 640,592
Weighted-average interest rate during period	1.64%	0.13%	1.27%	0.09%
FHLB Borrowings [Member]
Short-Term Debt [Line Items]
Amount outstanding at period end	$ 900,000		$ 900,000		$ 1,425,000
Weighted-average interest at period end	5.45%		5.45%		4.70%
Average amount outstanding during period	$ 765,217	$ 405,163	$ 1,429,121	$ 731,982
Maximum amount at any month end during period	$ 900,000	$ 1,000,000	$ 3,100,000	$ 1,100,000
Weighted-average interest rate during period	5.39%	2.34%	5.01%	0.84%