Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended					3 Months Ended		6 Months Ended		12 Months Ended	3 Months Ended
	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011	Jun. 30, 2012 Other liabilities	Dec. 31, 2011 Other liabilities	Jun. 30, 2012 PUERTO RICO	Jun. 30, 2011 PUERTO RICO	Jun. 30, 2012 PUERTO RICO	Jun. 30, 2011 PUERTO RICO	Dec. 31, 2010 PUERTO RICO	Jun. 30, 2012 PUERTO RICO Westernbank Assets Capital Gain Treatment [Member]	Jun. 30, 2012 PUERTO RICO Charge Off Treatment [Member]	Jun. 30, 2011 PUERTO RICO Charge Off Treatment [Member]	Jun. 30, 2011 PUERTO RICO Net [Member]	Jun. 30, 2011 PUERTO RICO Gross [Member]	Jun. 30, 2012 PUERTO RICO Commercial Banking [Member]
Income Taxes [Line Items]
Income Tax Reconciliation Prior Year Income Taxes														$ 53,600,000	$ 143,000,000
Income Taxes Paid						132,500,000						45,500,000	89,400,000
Income Tax Reconciliation Change In Enacted Tax Rate						0	0	0	103,287,000
Marginal Income Tax Rate								30.00%		39.00%	30.00%
Surtax Rate										5.00%
Deferred Tax Assets Net	572,744,000	429,691,000				588,000,000		588,000,000
Deferred Tax Liabilities	139,257,000	279,469,000		10,000,000	25,000,000
Income Tax Examination Minimum Likelihood Of Tax Benefits Being Realized Upon Ultimate Settlement	50.00%
Deferred Tax Assets Valuation Allowance	1,260,597,000	1,259,358,000
Unrecognized Tax Benefits Interest On Income Taxes Accrued	6,400,000	5,500,000
Income Tax Examination Penalties Accrued	0	0
Unrecognized Tax Benefits That Would Impact Effective Tax Rate	24,900,000		33,400,000
Significant Change In Unrecognized Tax Benefits Is Reasonably Possible Amount Of Unrecorded Benefit	11,000,000
Adjusted Marginal Income Tax Rate										40.95%
Effective Income Tax Rate Continuing Operations						640.00%	(53.00%)	(118.00%)	47.00%							20.00%
Preferential Tax Rate											15.00%
Prepaid Taxes	107,827,000	17,441,000									72,900,000
Reduction In Deferred Tax Liability						$ 72,900,000