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	Sep. 30, 2013		Dec. 31, 2012		Sep. 30, 2012
Financing Receivable, Impaired [Line Items]
Total impaired loans	$ 176,298		$ 204,545		$ 233,014
Allowance for loan losses related to impaired loans	14,329
Financing Receivable [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with an allowance for loan loss required	99,437	[1]	89,983	[1]	120,060	[1]
Impaired loans with no allowance for loan loss required	76,861		114,562		112,954
Total impaired loans	176,298	[2]	204,545	[2]	233,014	[2]
Allowance for loan losses related to impaired loans	4,400		13,575		19,818
Troubled debt restructurings	$ 115,003		$ 126,473		$ 147,196

[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.