Note Income taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Income Taxes [Line Items]
Deferred Tax Assets Net	$ 1,185,302		$ 1,185,302		$ 1,035,110
Unrecognized Tax Benefits Interest On Income Taxes Accrued	3,100		3,100		2,700
Unrecognized Tax Benefits That Would Impact Effective Tax Rate	10,200		10,200		9,000
Significant Change In Unrecognized Tax Benefits Is Reasonably Possible Amount Of Unrecorded Benefit	4,700		4,700
Recognized Tax Benefits Current Interest On Income Taxes Accrued	328	$ 307
Deferred Tax Liabilities	82,580		82,580		154,049
Deferred Tax Assets Valuation Allowance	498,084		498,084		447,824
Income Tax Expense Benefit	(28,560)	35,732	(6,405)	$ 68,738
Popular, Inc. Holding Co.
Income Taxes [Line Items]
Deferred Tax Assets Valuation Allowance	79,000		79,000
Income Tax Expense Benefit	0	0	0	0
Closing Agreement with the Puerto Rico Department of Treasury
Income Taxes [Line Items]
Income Tax Expense Benefit	108,900
FDIC Termination Agreement
Income Taxes [Line Items]
Income Tax Expense Benefit	45,000
"Deemed sale" incremental tax liability at the capital gains rate | Closing Agreement with the Puerto Rico Department of Treasury
Income Taxes [Line Items]
Income Tax Expense Benefit	49,800
Increase in the deferred tax asset due to increase in the tax basis of the loans | Closing Agreement with the Puerto Rico Department of Treasury
Income Taxes [Line Items]
Income Tax Expense Benefit	158,700
Other liabilities
Income Taxes [Line Items]
Deferred Tax Liabilities	1,500		1,500		1,300
PUERTO RICO
Income Taxes [Line Items]
Deferred Tax Assets Net	837,000		837,000
Deferred Tax Liabilities	60,397		60,397		128,615
Deferred Tax Assets Valuation Allowance	78,676		78,676		67,263
Income Tax Expense Benefit	(28,560)	$ 35,732	(6,405)	$ 68,738
UNITED STATES
Income Taxes [Line Items]
Deferred Tax Assets Net	347,000		347,000
Deferred Tax Liabilities	22,183		22,183		25,434
Deferred Tax Assets Valuation Allowance	419,408		419,408		$ 380,561
Deferred Tax Assets	$ 766,000		$ 766,000