Securities Sold Under Agreements To Repurchase And Other Short-Term Borrowings (Additional Information For Short-Term Borrowings) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase	$ 941,706	$ 839,144
Federal funds purchased	223,000	236,500
At End Of Year [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Federal funds purchased	223,000	236,500
Federal funds purchased, Rate	0.12%	0.19%
Average During Year [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Federal funds purchased	122,656	75,753	175,934
Federal funds purchased, Rate	0.14%	0.21%	0.20%
Highest Month-End Balance During Year [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Federal funds purchased	282,000	256,000	713,000
At End Of Year [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase	290,856	289,144	270,096
Securities sold under agreements to repurchase, Rate	0.20%	0.25%	0.41%
Average During Year [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase	310,355	312,728	277,447
Securities sold under agreements to repurchase, Rate	0.22%	0.36%	0.55%
Highest Month-End Balance During Year [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase	$ 342,795	$ 405,913	$ 295,402