Borrowings (Summary Of Securities Sold Under Agreements To Repurchase And Other Borrowings) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Assets Sold under Agreements to Repurchase [Line Items]
Amount	$ 2,800,000	$ 3,500,000
Securities sold under agreements to repurchase
Assets Sold under Agreements to Repurchase [Line Items]
Amount	$ 512,691	$ 440,431
Rate	0.39%	0.91%
Fed funds purchased
Assets Sold under Agreements to Repurchase [Line Items]
Amount	$ 740,000	$ 600,000
Rate	0.08%	1.59%
Line of credit | Paycheck Protection Program Liquidity Facility
Assets Sold under Agreements to Repurchase [Line Items]
Amount	$ 436,114	$ 0
Rate	0.35%	0.00%
Securities sold under agreements to repurchase and other borrowings
Assets Sold under Agreements to Repurchase [Line Items]
Amount	$ 1,688,805	$ 1,040,431
Rate	0.24%	1.30%
Original maturity of one year or less | Securities sold under agreements to repurchase
Assets Sold under Agreements to Repurchase [Line Items]
Amount	$ 312,691	$ 240,431
Rate	0.20%	0.19%
Original maturity of greater than one year, non-callable | Securities sold under agreements to repurchase
Assets Sold under Agreements to Repurchase [Line Items]
Amount	$ 200,000	$ 200,000
Rate	0.68%	1.78%