Allowance for Loan Losses, Allowance for Losses on Lending-Related Commitments and Impaired Loans 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, 2014		Dec. 31, 2013		Mar. 31, 2013
Financing Receivable, Impaired [Line Items]
Impaired loans with an allowance for loan loss required	$ 86,381	[1]	$ 92,184	[1]	$ 101,565	[1]
Impaired loans with no allowance for loan loss required	56,596		70,045		101,989
Total impaired loans	142,977	[2]	162,229	[2]	203,554	[2]
Allowance for loan losses related to impaired loans	8,197		8,265		14,607
Financing Receivable [Member]
Financing Receivable, Impaired [Line Items]
Allowance for loan losses related to impaired loans	4,000
TDRs	$ 92,517		$ 107,103		$ 116,345

[1] 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.

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