Borrowings (Summary Of Securities Sold Under Agreements To Repurchase And Other Borrowings) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Assets Sold under Agreements to Repurchase [Line Items]
Total securities sold under agreements to repurchase	$ 740,526	$ 834,400
Fed funds purchased	209,000	317,000
Securities sold under agreements to repurchase and other borrowings	949,526	1,151,400
Original maturity of one year or less [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total securities sold under agreements to repurchase	340,526	334,400
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	$ 400,000	$ 500,000
Securities Sold under Agreements to Repurchase [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Rate (as a percent)	1.82%	1.93%
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)	0.16%	0.15%
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)	3.09%	3.04%
Federal Funds Purchased [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Rate (as a percent)	0.46%	0.21%
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Rate (as a percent)	1.53%	1.47%