Carrying Amount of Loans Acquired as Part of the Westernbank FDIC-Assisted Transaction (Detail) (Acquired loans in an FDIC assisted transaction, Westernbank Puerto Rico, USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount	$ 4,265,065	$ 4,539,928
Less: Allowance for loan losses	48,257
Carrying amount, net of allowance	4,216,808	4,539,928
Credit Impaired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount	638,430	645,549
Less: Allowance for loan losses	9,624
Carrying amount, net of allowance	628,806	645,549
Credit Impaired Loans | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount	223,946	247,654
Credit Impaired Loans | Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount	3,860	8,257
Credit Impaired Loans | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount	313,339	292,341
Credit Impaired Loans | Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount	88,051	87,062
Credit Impaired Loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount	9,234	10,235
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount	2,197,335	2,381,254
Commercial real estate | Non-credit Impaired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount	1,973,389	2,133,600
Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount	90,304	126,126
Commercial and Industrial | Non-credit Impaired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount	86,444	117,869
Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount	633,782	634,207
Construction | Non-credit Impaired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount	320,443	341,866
Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount	1,220,741	1,243,941
Mortgages | Non-credit Impaired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount	1,132,690	1,156,879
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount	122,903	154,400
Consumer | Non-credit Impaired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount	113,669	144,165
Non-credit Impaired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount	3,626,635	3,894,379
Less: Allowance for loan losses	38,633
Carrying amount, net of allowance	$ 3,588,002	$ 3,894,379