Allowance for loan losses - Additional Information (Detail) (USD $)	3 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2012	Mar. 31, 2012	Dec. 31, 2011
Financing Receivable, Modifications [Line Items]
Financing Receivable Modifications Recorded Investment	$ 1,000,000,000	$ 1,000,000,000		$ 881,000,000
Financing Receivable Credit Quality Additional Information		Risk ratings scales 10 through 14 conform to regulatory ratings. The assignment of the obligor risk rating is based on relevant information about the ability of borrowers to service their debts such as current financial information, historical payment experience, credit documentation, public information, and current economic trends, among other factors.
Credit Card T D R Modification Time Period	24	24
Historical Loss Window Commercial Construction	3
Historical Loss Window Consumer Mortgage	18
Trend Factor Base Loss Commercial Construction Legacy	12
Trend Factor Base Loss Consumer Mortgage	6
Change Allowance For Loan Losses Change In Methodology			40,500,000
Change Allowance For Loan Losses Loan Groupings			7,900,000
Look Back Period Recent Trends Previous	6
Look Back Period Recent Trends Current	12
Change Allowance For Loan Losses Look Back Period			28,100,000
Change Allowance For Loan Losses Additional Enhancements			4,500,000
Change Due Environmental Factor Reserves			15,700,000
Net Impact Revisions			24,800,000
Recorded Investment Loan Split	27,000,000	27,000,000
Charge Offs Included Recorded Investment Loan Split	7,000,000	7,000,000
Recorded Investment Period End	21,000,000	21,000,000
Allowance Loans Modified Loan Split	357,000	357,000
Banco Popular De Puerto Rico [Member]
Financing Receivable, Modifications [Line Items]
Change Allowance For Loan Losses Loan Groupings			1,800,000
Change Allowance For Loan Losses Look Back Period			24,000,000
Change Allowance For Loan Losses Additional Enhancements			600,000
Banco Popular North America [Member]
Financing Receivable, Modifications [Line Items]
Change Allowance For Loan Losses Loan Groupings			9,700,000
Change Allowance For Loan Losses Look Back Period			4,100,000
Change Allowance For Loan Losses Additional Enhancements			3,900,000
Loan | Commercial Real Estate Construction Financing Receivable Member
Financing Receivable, Modifications [Line Items]
Loans And Leases Receivable Impaired Commitment To Lend	21,000	21,000		152,000
Loan | Commercial Portfolio Segment Member
Financing Receivable, Modifications [Line Items]
Loans And Leases Receivable Impaired Commitment To Lend	$ 3,000,000	$ 3,000,000		$ 3,000,000