Borrowings (Summary Of Securities Sold Under Agreements To Repurchase And Other Borrowings) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Assets Sold under Agreements to Repurchase [Line Items]
Total securities sold under agreements to repurchase	$ 469,330	$ 440,431
Fed funds purchased	526,025	600,000
Securities sold under agreements to repurchase and other borrowings	995,355	1,040,431
Original maturity of one year or less [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total securities sold under agreements to repurchase	269,330	240,431
Original maturity of greater than one year, non-callable [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total securities sold under agreements to repurchase	$ 200,000	$ 200,000
Securities Sold under Agreements to Repurchase [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Rate (as a percent)	0.43%	0.91%
Securities Sold under Agreements to Repurchase [Member] | Original maturity of one year or less [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Rate (as a percent)	0.13%	0.19%
Securities Sold under Agreements to Repurchase [Member] | Original maturity of greater than one year, non-callable [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Rate (as a percent)	0.84%	1.78%
Federal Funds Purchased [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Rate (as a percent)	0.08%	1.59%
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Rate (as a percent)	0.25%	1.30%