Note Goodwill and other intangible assets - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Jun. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Jul. 31, 2017
Goodwill and Intangible Assets Disclosure [Line Items]
Indefinite Lived Intangible Assets	$ 6,100			$ 6,100		$ 6,100
Amortization Of Intangible Assets	$ 2,345	$ 3,097		7,034	$ 9,308
Goodwill Purchase Accounting Adjustments				0	4,707
Goodwil, Acquired During Period				$ 0	0
Fair Value Inputs Discount Rate				4.72%		5.97%
FDIC Assisted Partial Acquisition Of Doral Bank
Goodwill and Intangible Assets Disclosure [Line Items]
Goodwill Purchase Accounting Adjustments			$ 4,700
Goodwil, Acquired During Period			$ 167,800
Maximum
Goodwill and Intangible Assets Disclosure [Line Items]
Fair Value Inputs Discount Rate				14.49%
Minimum
Goodwill and Intangible Assets Disclosure [Line Items]
Fair Value Inputs Discount Rate				11.58%
Banco Popular de Puerto Rico and Banco Popular North America
Goodwill and Intangible Assets Disclosure [Line Items]
Percentage Of Goodwill							98.00%
BPNA
Goodwill and Intangible Assets Disclosure [Line Items]
Step 1 Fair Value Excess Over Carrying Amount							$ 183,000
Percentage excess of fair value of reporting unit over equity value							11.00%
BPPR
Goodwill and Intangible Assets Disclosure [Line Items]
Goodwill Purchase Accounting Adjustments				$ 0	0
Step 1 Fair Value Excess Over Carrying Amount							$ 871,000
Percentage excess of fair value of reporting unit over equity value							26.00%
Goodwil, Acquired During Period				$ 0	$ 0