Borrowings (Summary Of Securities Sold Under Agreements To Repurchase And Other Borrowings) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Assets Sold under Agreements to Repurchase [Line Items]
Total securities sold under agreements to repurchase	$ 440,431	$ 236,874
Fed funds purchased	600,000	345,000
Securities sold under agreements to repurchase and other borrowings	1,040,431	581,874
Original maturity of one year or less [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total securities sold under agreements to repurchase	240,431	236,874
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	$ 0
Securities Sold under Agreements to Repurchase [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Rate (as a percent)	0.91%	0.35%
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)	0.19%	0.35%
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)	1.78%	0.00%
Federal Funds Purchased [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Rate (as a percent)	1.59%	2.52%
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Rate (as a percent)	1.30%	1.64%