Fair Values of Major Classes of Identifiable Assets Acquired and Liabilities Assumed (Detail) (Westernbank Puerto Rico, USD $) In Thousands	Apr. 30, 2010
Business Acquisition [Line Items]
Assets	$ 2,337,748
Total assets	8,274,310
Total liabilities	8,274,310
Book value prior to purchase accounting adjustments
Business Acquisition [Line Items]
Total assets	9,142,359
Total liabilities	2,394,095
Book value prior to purchase accounting adjustments | Cash and money market investments
Business Acquisition [Line Items]
Assets	358,132
Book value prior to purchase accounting adjustments | Investment in Federal Home Loan Bank stock
Business Acquisition [Line Items]
Assets	58,610
Book value prior to purchase accounting adjustments | Loans
Business Acquisition [Line Items]
Assets	8,554,744
Book value prior to purchase accounting adjustments | Covered other real estate owned
Business Acquisition [Line Items]
Assets	125,947
Book value prior to purchase accounting adjustments | Other assets
Business Acquisition [Line Items]
Assets	44,926
Book value prior to purchase accounting adjustments | Deposits
Business Acquisition [Line Items]
Liabilities	2,380,170
Book value prior to purchase accounting adjustments | Other liabilities
Business Acquisition [Line Items]
Liabilities	13,925
Fair value adjustments
Business Acquisition [Line Items]
Assets	2,337,748
Total assets	(979,150)
Total liabilities	57,220
Fair value adjustments | Loans
Business Acquisition [Line Items]
Assets	(3,354,287)
Fair value adjustments | Covered other real estate owned
Business Acquisition [Line Items]
Assets	(73,867)
Fair value adjustments | Core deposit intangible
Business Acquisition [Line Items]
Assets	24,415
Fair value adjustments | Goodwill
Business Acquisition [Line Items]
Assets	86,841
Fair value adjustments | Deposits
Business Acquisition [Line Items]
Liabilities	11,465
Fair value adjustments | Contingent liability on unfunded loan commitments
Business Acquisition [Line Items]
Liabilities	45,755
Additional consideration
Business Acquisition [Line Items]
Total assets	111,101
Total liabilities	5,822,995
Additional consideration | Receivable from FDIC (associated to the note issued to the FDIC)
Business Acquisition [Line Items]
Assets	111,101
Additional consideration | Note issued to the FDIC
Business Acquisition [Line Items]
Liabilities	5,770,495
Additional consideration | Equity appreciation instrument
Business Acquisition [Line Items]
Liabilities	52,500
Cash and money market investments
Business Acquisition [Line Items]
Assets	358,132
Investment in Federal Home Loan Bank stock
Business Acquisition [Line Items]
Assets	58,610
Loans
Business Acquisition [Line Items]
Assets	5,200,457
Covered other real estate owned
Business Acquisition [Line Items]
Assets	52,080
Core deposit intangible
Business Acquisition [Line Items]
Assets	24,415
Receivable from FDIC (associated to the note issued to the FDIC)
Business Acquisition [Line Items]
Assets	111,101
Other assets
Business Acquisition [Line Items]
Assets	44,926
Goodwill
Business Acquisition [Line Items]
Assets	86,841
Deposits
Business Acquisition [Line Items]
Liabilities	2,391,635
Note issued to the FDIC
Business Acquisition [Line Items]
Liabilities	5,770,495
Equity appreciation instrument
Business Acquisition [Line Items]
Liabilities	52,500
Contingent liability on unfunded loan commitments
Business Acquisition [Line Items]
Liabilities	45,755
Other liabilities
Business Acquisition [Line Items]
Liabilities	$ 13,925