Activity in Allowance for Loan Losses Related to Acquired Loans (Detail) (USD $) In Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of period	$ 736,505	$ 793,225
Provision for loan losses	144,317	219,636
Charge-offs	171,849	342,950
Balance at end of period	746,847	746,847
Credit Impaired Loans | Acquired loans in an FDIC assisted transaction | Westernbank Puerto Rico
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of period	5,297
Provision for loan losses	43,555	52,682
Charge-offs	595	4,425
Balance at end of period	$ 48,257	$ 48,257