Income taxes - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Income Taxes
Deferred Tax Assets Net	$ 909,638		$ 909,638		$ 1,049,895
Deferred Tax Assets Valuation Allowance	492,409		492,409		496,307
Deferred Tax Liabilities	135,438		135,438		96,406
Unrecognized Tax Benefits Interest On Income Taxes Accrued	3,100		3,100		2,800
Unrecognized Tax Benefits That Would Impact Effective Tax Rate	10,100		10,100		$ 9,000
Significant Change In Unrecognized Tax Benefits Is Reasonably Possible Amount Of Unrecorded Benefit	3,200		3,200
Recognized Tax Benefits Current Interest On Income Taxes Accrued			317	$ 477
Income Tax Expense Benefit	41,370	$ 42,018	$ 131,923	35,613
Computed income tax at statutory rates			37.50%		39.00%
Closing Agreement with the Puerto Rico Department of Treasury
Income Taxes
Income Tax Expense Benefit				108,900
FDIC Termination Agreement
Income Taxes
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
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
Income Tax Expense Benefit				158,700
Other assets
Income Taxes
Deferred Tax Assets Net	900,000		$ 900,000		$ 1,000,000
Other liabilities
Income Taxes
Deferred Tax Liabilities	1,000		1,000		926
Popular, Inc Holding Co
Income Taxes
Deferred Tax Assets Valuation Allowance	99,800		99,800
PUERTO RICO
Income Taxes
Deferred Tax Assets Net	595,000		595,000
Deferred Tax Assets Valuation Allowance	99,766		99,766		89,852
Deferred Tax Liabilities	87,109		87,109		68,483
Income Tax Expense Benefit	$ 41,370	$ 42,018	$ 131,923	$ 35,613
Computed income tax at statutory rates	38.00%	39.00%	38.00%	39.00%
UNITED STATES
Income Taxes
Deferred Tax Assets Net	$ 313,000		$ 313,000
Deferred Tax Assets Valuation Allowance	392,643		392,643		406,455
Deferred Tax Assets	706,000		706,000
Deferred Tax Liabilities	$ 48,329		$ 48,329		$ 27,923