Stock-based compensation - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Executive Officers
Stock-based compensation
Total unrecognized compensation cost related to non-vested restricted stock awards and performance shares to members of management	$ 10,500,000		$ 10,500,000
Total unrecognized compensation cost related to non-vested restricted stock awards and performance shares to members of management, period of recognition (in years)			2 years
Fair value of stocks vested at grant date			$ 7,100,000
Fair Market Value of stock vested at vesting date			10,500,000
Windfall Net Of Shortfall			$ 2,500,000
Restricted Stock Award | Executive Officers
Stock-based compensation
Stock granted	0	266	120,105	213,511
Restricted Stock Expense	$ 1,300,000	$ 1,000,000.0	$ 7,500,000	$ 6,700,000
Incentive award, tax benefit	$ 300,000	$ 200,000	$ 1,400,000	$ 1,100,000
Restricted Stock Units (RSUs)
Stock-based compensation
Stock-Based Compensation, vesting rights			Unless otherwise stated in an agreement, the compensation cost associated with the shares of restricted stock is determined based on a two-prong vesting schedule. The first part is vested ratably over five years commencing at the date of grant (“the graduated vesting portion”) and the second part is vested at termination of employment after attainment of 55 years of age and 10 years of service (“the retirement vesting portion”). The graduated vesting portion is accelerated at termination of employment after attaining 55 years of age and 10 years of service. The vesting schedule for restricted shares granted on or after 2014 and prior to 2021 was modified as follows, the graduated vesting portion is vested ratably over four years commencing at the date of the grant and the retirement vesting portion is vested at termination of employment after attainment of the earlier of 55 years of age and 10 years of service or 60 years of age and 5 years of service. The graduated vesting portion is accelerated at termination of employment after attaining the earlier of 55 years of age and 10 years of service or 60 years of age and 5 years of service. Restricted stock granted on or after 2021 will vest ratably in equal annual installments over a period of 4 years or 3 years, depending on the classification of the employee.
Restricted Stock Units (RSUs) | TARP Interim Final Rule
Stock-based compensation
Stock-Based Compensation, vesting rights			The restricted stock granted under the Incentive Plan to employees becomes vested based on the employees’ continued service with Popular. Unless otherwise stated in an agreement, the compensation cost associated with the shares of restricted stock is determined based on a two-prong vesting schedule. The first part is vested ratably over five years commencing at the date of grant (“the graduated vesting portion”) and the second part is vested at termination of employment after attainment of 55 years of age and 10 years of service (“the retirement vesting portion”). The graduated vesting portion is accelerated at termination of employment after attaining 55 years of age and 10 years of service. The vesting schedule for restricted shares granted on or after 2014 and prior to 2021 was modified as follows, the graduated vesting portion is vested ratably over four years commencing at the date of the grant and the retirement vesting portion is vested at termination of employment after attainment of the earlier of 55 years of age and 10 years of service or 60 years of age and 5 years of service. The graduated vesting portion is accelerated at termination of employment after attaining the earlier of 55 years of age and 10 years of service or 60 years of age and 5 years of service. Restricted stock granted on or after 2021 will vest ratably in equal annual installments over a period of 4 years or 3 years, depending on the classification of the employee.
Restricted Stock Units (RSUs) | Directors
Stock-based compensation
Stock granted	545	783	20,079	43,084	43,866
Restricted Stock Expense	$ 42,000	$ 28,000	$ 1,900,000	$ 1,500,000
Incentive award, tax benefit	$ 8,000	$ 5,000	300,000	$ 300,000
Fair Market Value of stock vested at vesting date			$ 1,600,000
Performance Based Shares | Executive Officers
Stock-based compensation
Stock granted	0	0	71,374	64,815
Restricted Stock Expense	$ 300,000	$ 300,000	$ 4,900,000	$ 3,100,000
Incentive award, tax benefit	$ 12,000	$ 24,000	$ 500,000	$ 300,000
Stock-Based Compensation, vesting rights			The number of shares that will ultimately vest ranges from 50% to a 150% of target based on both market (TSR) and performance (EPS, ROA and ROATCE) conditions. The performance shares vest at the end of the three-year performance cycle. If a participant terminates employment after attaining the earlier of 55 years of age and 10 years of service or 60 years of age and 5 years of service, the performance shares shall continue outstanding and vest at the end of the performance cycle.