Securities Sold Under Agreements To Repurchase And Other Short-Term Borrowings (Summary Of Securities Sold Under Agreements To Repurchase And Other Short-Term Borrowings) (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Securities Sold Under Agreements to Repurchase and Other Short-term Borrowings [Line Items]
Securities sold under agreements to repurchase	$ 1,076,160	$ 941,706
Federal funds purchased	0	223,000
Total securities sold under agreements to repurchase and other short-term borrowings	1,076,160	1,164,706
Original Maturity Of One Year Or Less [Member]
Securities Sold Under Agreements to Repurchase and Other Short-term Borrowings [Line Items]
Securities sold under agreements to repurchase	326,160	290,856
Callable At The Option Of The Counterparty [Member]
Securities Sold Under Agreements to Repurchase and Other Short-term Borrowings [Line Items]
Securities sold under agreements to repurchase	300,000	400,000
Non-Callable [Member]
Securities Sold Under Agreements to Repurchase and Other Short-term Borrowings [Line Items]
Securities sold under agreements to repurchase	$ 450,000	$ 250,850