Allowance For Loan Losses, Allowance For Losses On Lending-Related Commitments And Impaired Loans (Summary Of Impaired Loans, Including Restructured Loans) (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012		Mar. 31, 2012
Total impaired loans	$ 203,554	[1]	$ 204,545	[1]	$ 251,963	[1]
Allowance for loan losses related to impaired loans	14,607		13,575		20,989
Restructured loans	116,345		126,473		165,046
Impaired Loans With A Related ASC 310 Allowance Recorded [Member]
Total impaired loans	101,565	[2]	89,983	[2]	137,805	[2]
Impaired Financing Receivables With No Related Allowance [Member]
Total impaired loans	$ 101,989		$ 114,562		$ 114,158

[1] Impaired loans are considered by the Company to be non-accrual loans, restructured loans or loans with principal and/or interest at risk, even if the loan is current with all payments of principal and interest.

[2] These impaired loans require an allowance for loan losses because the estimated fair value of the loans or related collateral is less than the recorded investment in the loans.