Note Segment reporting (Results of Operations) (Detail) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2018		Sep. 30, 2017	Sep. 30, 2018		Sep. 30, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Net Interest income (expense)	$ 451,469		$ 378,171	$ 1,258,652		$ 1,114,748
Provision (reversal) for loan losses	54,387		160,759	185,504		253,936
Non interest Income	151,021		100,374	499,327		333,036
Amortization of intangibles	2,324		2,345	6,973		7,034
Depreciation expense	13,508		12,038	39,083		35,966
Other operating expenses	349,605		302,705	979,051		892,241
Income tax expense (benefit)	42,018		(19,966)	35,613		48,772
Net income (loss)	140,648		20,664	511,755		209,835
Segment assets	47,919,428		42,601,267	47,919,428		42,601,267	$ 44,277,337
Reportable Segment
Segment Reporting Information [Line Items]
Net Interest income (expense)	464,720		392,605	1,300,181		1,159,091
Provision (reversal) for loan losses	54,421		160,721	185,579		259,583
Non interest Income	141,151		93,153	467,167		304,870
Amortization of intangibles	2,324		2,345	6,973		7,034
Depreciation expense	13,320		11,879	38,535		35,487
Other operating expenses	326,267		285,386	912,470		837,120
Income tax expense (benefit)	49,860		(12,821)	56,847		70,055
Net income (loss)	159,679		38,248	566,944		254,682
Segment assets	47,615,136		42,330,871	47,615,136		42,330,871
Intersegment Elimination
Segment Reporting Information [Line Items]
Net Interest income (expense)	3		7	5		(207)
Provision (reversal) for loan losses	0		0	0		0
Non interest Income	(141)		(141)	(420)		(431)
Amortization of intangibles	0		0	0		0
Depreciation expense	0		0	0		0
Other operating expenses	(136)		(138)	(409)		(414)
Income tax expense (benefit)	0		0	0		(93)
Net income (loss)	(2)		4	(6)		(131)
Segment assets	(112,222)		(24,615)	(112,222)		(24,615)
Corporate
Segment Reporting Information [Line Items]
Net Interest income (expense)	(13,251)		(14,434)	(41,529)		(44,343)
Provision (reversal) for loan losses	(34)		38	(75)		308
Non interest Income	9,960		7,277	33,698		29,616
Amortization of intangibles	0		0	0		0
Depreciation expense	188		159	548		479
Other operating expenses	23,995		17,944	68,766		57,145
Income tax expense (benefit)	(8,070)		(7,360)	(21,505)		(23,819)
Net income (loss)	(19,370)		(17,938)	(55,565)		(48,840)
Segment assets	5,478,884		5,003,304	5,478,884		5,003,304
Eliminations
Segment Reporting Information [Line Items]
Net Interest income (expense)	0		0	0		0
Provision (reversal) for loan losses	0		0	0		(5,955)
Non interest Income	(90)		(56)	(1,538)		(1,450)
Amortization of intangibles	0		0	0		0
Depreciation expense	0		0	0		0
Other operating expenses	(657)		(625)	(2,185)		(2,024)
Income tax expense (benefit)	228		215	271		2,536
Net income (loss)	339		354	376		3,993
Segment assets	(5,174,592)		(4,732,908)	(5,174,592)		(4,732,908)
Banco Popular de Puerto Rico | Reportable Segment
Segment Reporting Information [Line Items]
Net Interest income (expense)	388,533		321,145	1,073,522		951,024
Provision (reversal) for loan losses	51,911		118,177	154,805		198,668
Non interest Income	135,762		88,170	452,577		290,042
Amortization of intangibles	2,157		2,178	6,474		6,535
Depreciation expense	11,135		9,751	32,069		29,296
Other operating expenses	282,124		243,564	777,574		713,594
Income tax expense (benefit)	39,421		(8,704)	41,088		56,946
Net income (loss)	137,547		44,349	514,089		236,027
Segment assets	38,338,571		33,031,839	38,338,571		33,031,839
Banco Popular de Puerto Rico | Commercial Banking | Reportable Segment
Segment Reporting Information [Line Items]
Net Interest income (expense)	145,397		132,101	430,341		380,761
Provision (reversal) for loan losses	25,580		27,647	56,027		27,970
Non interest Income	23,630		19,733	60,122		60,496
Amortization of intangibles	50		54	153		158
Depreciation expense	4,697		4,386	13,327		12,994
Other operating expenses	78,628		61,843	199,528		177,278
Income tax expense (benefit)	11,068		11,925	52,640		60,780
Net income (loss)	49,004		45,979	168,788		162,077
Segment assets	28,247,478		21,258,790	28,247,478		21,258,790
Banco Popular de Puerto Rico | Consumer and Retail Banking | Reportable Segment
Segment Reporting Information [Line Items]
Net Interest income (expense)	241,920		186,827	639,149		564,956
Provision (reversal) for loan losses	26,331		90,530	98,778		170,698
Non interest Income	88,866		46,022	220,690		162,613
Amortization of intangibles	1,069		1,066	3,209		3,206
Depreciation expense	6,287		5,207	18,284		15,759
Other operating expenses	183,626		164,981	518,147		492,939
Income tax expense (benefit)	27,436		(22,811)	46,625		(12,760)
Net income (loss)	86,037		(6,124)	174,796		57,727
Segment assets	22,672,941		18,501,519	22,672,941		18,501,519
Banco Popular de Puerto Rico | Other Financial Services | Reportable Segment
Segment Reporting Information [Line Items]
Net Interest income (expense)	1,232		2,213	4,066		5,295
Provision (reversal) for loan losses	0		0	0		0
Non interest Income	23,663		22,473	69,876		67,130
Amortization of intangibles	1,038		1,058	3,112		3,171
Depreciation expense	151		158	458		543
Other operating expenses	20,279		16,809	52,679		43,606
Income tax expense (benefit)	917		2,182	5,711		8,926
Net income (loss)	2,510		4,479	11,982		16,179
Segment assets	336,311		522,008	336,311		522,008
Banco Popular de Puerto Rico | Eliminations | Reportable Segment
Segment Reporting Information [Line Items]
Net Interest income (expense)	(16)		4	(34)		12
Provision (reversal) for loan losses	0		0	0		0
Non interest Income	(397)		(58)	101,889		(197)
Amortization of intangibles	0		0	0		0
Depreciation expense	0		0	0		0
Other operating expenses	(409)		(69)	7,220		(229)
Income tax expense (benefit)	0		0	(63,888)		0
Net income (loss)	(4)	[1]	15	158,523	[1]	44
Segment assets	(12,918,159)		(7,250,478)	(12,918,159)		(7,250,478)
Popular U.S. | Reportable Segment
Segment Reporting Information [Line Items]
Net Interest income (expense)	76,184		71,453	226,654		208,274
Provision (reversal) for loan losses	2,510		42,544	30,774		60,915
Non interest Income	5,530		5,124	15,010		15,259
Amortization of intangibles	167		167	499		499
Depreciation expense	2,185		2,128	6,466		6,191
Other operating expenses	44,279		41,960	135,305		123,940
Income tax expense (benefit)	10,439		(4,117)	15,759		13,202
Net income (loss)	22,134		(6,105)	52,861		18,786
Segment assets	$ 9,388,787		$ 9,323,647	$ 9,388,787		$ 9,323,647

[1] Includes the impact of the Termination Agreement with the FDIC and the Tax Closing Agreement entered into in connection with the FDIC transaction. These transactions resulted in a gain of $102.8 million reported in the non-interest income line, other operating expenses of $8.1 million and a net tax benefit of $63.9 million. Refer to Notes 9 and 31 to the Consolidated Financial Statements for additional information.