FDIC loss share - Additional Information (Detail) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Loss Share Indemnification Asset [Line Items]
Percent Calculation Intrinsic Loss Estimate	925,000,000
Calculation Percent Asset Discount Per Bid	1,100,000,000
Intrinsic Loss Estimate	4,600,000,000
Servicing Amount Period Trueup Payment	twelve-month period
Payment Percentage True Up Payment [Member]
Loss Share Indemnification Asset [Line Items]
Fixed Percentage True Up Payment	50.00%
Intrinsic Loss Estimate Trueup Payment [Member]
Loss Share Indemnification Asset [Line Items]
Fixed Percentage True Up Payment	20.00%
Asset Discount Trueup Payment [Member]
Loss Share Indemnification Asset [Line Items]
Fixed Percentage True Up Payment	25.00%
Cumulative Shared Loss Payments Trueup Payment [Member]
Loss Share Indemnification Asset [Line Items]
Fixed Percentage True Up Payment	25.00%
Servicing Percentage Trueup Payment [Member]
Loss Share Indemnification Asset [Line Items]
Fixed Percentage True Up Payment	1.00%
Banco Popular De Puerto Rico [Member]
Loss Share Indemnification Asset [Line Items]
FDIC Loss sharing agreements, reimbursement percentage	80	80	80
Banco Popular De Puerto Rico [Member] | Other Consumer And Commercial Loans [Member]
Loss Share Indemnification Asset [Line Items]
Loss Share Agreements Reimbursement Term	8
Federal Deposit Insurance Corporation [Member]
Loss Share Indemnification Asset [Line Items]
FDIC Loss sharing agreements, reimbursement percentage	80	80	80
Contingency For True Up Payment To F D I C Discounted Value	100,000,000	94,000,000	98,000,000
Federal Deposit Insurance Corporation [Member] | Single Family Residential Mortgage
Loss Share Indemnification Asset [Line Items]
Loss Sharing Term	10
Federal Deposit Insurance Corporation [Member] | Other Consumer And Commercial Loans [Member]
Loss Share Indemnification Asset [Line Items]
Loss Sharing Term	5