Commitments and contingencies - Additional Information (Detail) - Financing Receivable Recorded Investment Class Of Financing Receivable Domain			3 Months Ended			6 Months Ended
		Jul. 31, 2015 USD ($)	Jun. 30, 2015 USD ($) D	Mar. 31, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) D	Jun. 30, 2014 USD ($)	Jul. 30, 2015 USD ($)	Jul. 22, 2015 USD ($)	Dec. 31, 2014 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Commitments and Contingencies Disclosure [Line Items]
Unrecorded Unconditional Purchase Obligation Balance Sheet Amount			$ 9,000,000			$ 9,000,000				$ 9,000,000
True Up Payment Term | D			45			45
Loans And Leases Receivable Net Of Deferred Income	[1]		$ 22,435,145,000			$ 22,435,145,000				19,404,451,000
Write-off			(108,003,000)		$ (83,975,000)	(189,818,000)	$ (196,746,000)
Loans and Leases Receivable, Gross, Carrying Amount, Covered			689,650,000			689,650,000				2,542,662,000
F D I C Reimbursable Expenses			42,730,000		11,085,000	64,275,000	23,830,000
Transfer Of Portfolio Loans And Leases To Held For Sale 1						61,290,000	1,868,420,000
Reclassification Of Loans Expiration LSA			1,500,000,000			1,500,000,000
F D I C Indemnification Asset			392,947,000	$ 409,844,000	712,869,000	392,947,000	712,869,000			542,454,000	$ 798,460,000	$ 909,414,000
Segment, Continuing Operations [Member]
Commitments and Contingencies Disclosure [Line Items]
Other Than Temporary Impairment Losses Investments Portion Recognized In Earnings Net			(14,445,000)		0	(14,445,000)	0
Pending Dispute With the FDIC of November 25, 2014
Commitments and Contingencies Disclosure [Line Items]
Reclassification Of Loans Expiration LSA			248,700,000			248,700,000
Commercial Real Estate [Member]
Commitments and Contingencies Disclosure [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount, Covered			3,000			3,000				1,511,472,000
Commercial Real Estate Construction Financing Receivable Member
Commitments and Contingencies Disclosure [Line Items]
Loans And Leases Receivable Net Of Deferred Income			696,010,000			696,010,000				251,820,000
Write-off			(18,234,000)		(6,469,000)	(27,280,000)	(29,866,000)
Loans and Leases Receivable, Gross, Carrying Amount, Covered			0			0				70,336,000
Mortgages [Member]
Commitments and Contingencies Disclosure [Line Items]
Loans And Leases Receivable Net Of Deferred Income			7,225,823,000			7,225,823,000				6,502,886,000
Write-off			(12,221,000)		(13,259,000)	(26,801,000)	(25,179,000)
Loans and Leases Receivable, Gross, Carrying Amount, Covered			671,074,000			671,074,000				822,986,000
Consumer [Member]
Commitments and Contingencies Disclosure [Line Items]
Loans And Leases Receivable Net Of Deferred Income			3,843,278,000			3,843,278,000				3,870,271,000
Write-off			(27,923,000)		$ (33,261,000)	(60,140,000)	$ (68,138,000)
Loans and Leases Receivable, Gross, Carrying Amount, Covered			18,573,000			18,573,000				34,559,000
Covered Under Loss Sharing Agreements With F D I C [Member]
Commitments and Contingencies Disclosure [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount, Covered			689,650,000			689,650,000				2,542,662,000
Covered Under Loss Sharing Agreements With F D I C [Member] | Commercial Real Estate Construction Financing Receivable Member
Commitments and Contingencies Disclosure [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount, Covered			0			0				70,336,000
Covered Under Loss Sharing Agreements With F D I C [Member] | Mortgages [Member]
Commitments and Contingencies Disclosure [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount, Covered			671,074,000			671,074,000				822,986,000
Covered Under Loss Sharing Agreements With F D I C [Member] | Consumer [Member]
Commitments and Contingencies Disclosure [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount, Covered			18,573,000			18,573,000				34,559,000
Minimum Member
Commitments and Contingencies Disclosure [Line Items]
Loss Contingency Range Of Possible Loss Portion Not Accrued			0			0
Maximum Member
Commitments and Contingencies Disclosure [Line Items]
Loss Contingency Range Of Possible Loss Portion Not Accrued			32,600,000			32,600,000
Federal Deposit Insurance Corporation [Member]
Commitments and Contingencies Disclosure [Line Items]
Business Combination Contingent Consideration Liability			121,469,000			121,469,000				129,304,000
Banco Popular De Puerto Rico [Member] | Pending Dispute With the FDIC of November 25, 2014
Commitments and Contingencies Disclosure [Line Items]
F D I C Indemnification Asset			141,300,000			141,300,000
Banco Popular De Puerto Rico [Member] | Government | PR Government Direct Exposure [Member] | From PR Government And Public Corporations [Member]
Commitments and Contingencies Disclosure [Line Items]
Transfer Of Portfolio Loans And Leases To Held For Sale 1			75,000,000
Banco Popular De Puerto Rico [Member] | Arbitration With F D I C Regarding Reimbursement For Westernbank Loans [Member]
Commitments and Contingencies Disclosure [Line Items]
F D I C Indemnification Asset Cash Payments Received		$ 78,900,000
Total Unreimbursed F D I C Shared Loss Claims			307,900,000			307,900,000			$ 215,300,000
Unreimbursed Claims Submitted to the FDIC								$ 177,800,000
Unreimbursed Claims Yet To Be Submitted To The FDIC								$ 229,000,000
Banco Popular De Puerto Rico [Member] | Covered Under Loss Sharing Agreements With F D I C [Member] | Pending Dispute With the FDIC of November 25, 2014
Commitments and Contingencies Disclosure [Line Items]
Write-off						53,300,000
Loss Claim Disputed Amount			66,600,000			66,600,000
F D I C Reimbursable Expenses				$ 1,400,000
F D I C Reimbursable Expenses Clawed Back			1,700,000			1,700,000
Loss Contingency Increase In Damages Sought Value			1,700,000			1,700,000
Credit Concentration Risk Member | PR Government Indirect Exposure [Member] | Housing Bonds backed by GNMA, FNMA or residential CMOs
Commitments and Contingencies Disclosure [Line Items]
Concentration Of Risk Credit Facilities			50,000,000			50,000,000				49,000,000
Credit Concentration Risk Member | PR Government Indirect Exposure [Member] | Industrial Development Notes
Commitments and Contingencies Disclosure [Line Items]
Concentration Of Risk Credit Facilities			29,000,000			29,000,000				32,000,000
Credit Concentration Risk Member | Outstanding Balance [Member] | Government | PR Government Direct Exposure [Member]
Commitments and Contingencies Disclosure [Line Items]
Concentration Of Risk Credit Facilities			672,867,000			672,867,000				811,026,000
Loans And Leases Receivable Net Of Deferred Income			564,690,000			564,690,000				689,045,000
Investments			108,177,000			108,177,000				121,981,000
Credit Concentration Risk Member | Outstanding Balance [Member] | Government | PR Government Direct Exposure [Member] | From PR Government And Public Corporations [Member]
Commitments and Contingencies Disclosure [Line Items]
Concentration Of Risk Credit Facilities			184,513,000			184,513,000				336,459,000
Credit Concentration Risk Member | Outstanding Balance [Member] | Government | PR Government Direct Exposure [Member] | From Municipalities [Member]
Commitments and Contingencies Disclosure [Line Items]
Concentration Of Risk Credit Facilities			488,354,000			488,354,000				474,567,000
Credit Concentration Risk Member | Outstanding Balance [Member] | Government | PR Government Indirect Exposure [Member]
Commitments and Contingencies Disclosure [Line Items]
Loans and Leases Receivable, Consumer, Mortgage with PRHA			301,000,000			301,000,000				289,000,000
Credit Concentration Risk Member | Total [Member] | Government | PR Government Direct Exposure [Member]
Commitments and Contingencies Disclosure [Line Items]
Concentration Of Risk Credit Facilities			728,947,000			728,947,000				1,017,088,000
Credit Concentration Risk Member | Total [Member] | Government | PR Government Indirect Exposure [Member]
Commitments and Contingencies Disclosure [Line Items]
Concentration Of Risk Credit Facilities			380,000,000			380,000,000				370,000,000
Commitments To Extend Credit Member
Commitments and Contingencies Disclosure [Line Items]
Reserve of potential losses associated with unfunded loan commitments			$ 14,000,000			14,000,000				$ 13,000,000
Putative Class Action [Member] | Bpna [Member]
Commitments and Contingencies Disclosure [Line Items]
Litigation Settlement Amount						25,000
Potential Class Action Lawsuit Of Improper Job Classification [Member] | Bpna [Member]
Commitments and Contingencies Disclosure [Line Items]
Litigation Settlement Amount						800,000
Multiple Arbitration Proceedings Against Popular Securities And Two Other PR Broker Dealers [Member] | Popular Securities [Member]
Commitments and Contingencies Disclosure [Line Items]
Loss Contingency Aggregate Claims Damages Sought						99,000,000
Loss Contingency Claim Of One Single Arbitration Case						$ 78,000,000

[1] Non-covered loans held-in-portfolio at June 30, 2015 are net of $100 million in unearned income and exclude $202 million in loans held-for-sale. (December 31, 2014 - $94 million in unearned income and $106 million in loans held-for-sale.)