Note Allowance for loan losses (Allowance Movement) (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Financing Receivable, Allowance for Credit Losses
Balance at beginning of period		$ 569,348	$ 623,426
Provision (reversal) for loan losses		41,825	71,063
Charge-offs		(79,841)	(67,816)
Recoveries		19,296	13,905
Balance at end of period		550,628	640,578
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Specific ALLL		101,958	117,015
General ALLL		448,670	523,563
Ending balance: loans individually evaluated for impairment		1,034,037	981,223
Ending balance: loans collectively evaluated for impairment		25,613,671	23,621,325
Non-covered Loans held-in-portfolio		26,647,708		$ 26,507,889
Loans And Leases Receivable Covered And Not Covered Total Net Of Unearned Income		26,647,708	24,602,548
PUERTO RICO
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Non-covered Loans held-in-portfolio		19,996,350		19,883,472
PUERTO RICO | Non-covered loans
Financing Receivable, Allowance for Credit Losses
Balance at beginning of period		507,158	518,104
Provision (reversal) for loan losses		31,454	56,718
Charge-offs		(70,622)	(51,417)
Recoveries		16,393	10,190
Balance at end of period		484,383	533,595
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Specific ALLL		97,722	113,324
General ALLL		386,661	420,271
Ending balance: loans individually evaluated for impairment		1,001,861	966,297
Ending balance: loans collectively evaluated for impairment		18,994,489	16,773,383
Non-covered Loans held-in-portfolio		19,996,350	17,739,680
PUERTO RICO | Covered loans
Financing Receivable, Allowance for Credit Losses
Balance at beginning of period			33,244
Provision (reversal) for loan losses			1,730
Charge-offs			(1,448)
Recoveries			84
Balance at end of period			33,610
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Specific ALLL			0
General ALLL			33,610
Ending balance: loans individually evaluated for impairment			0
Ending balance: loans collectively evaluated for impairment			514,611
Loans covered under loss-sharing agreements with the FDIC			514,611
UNITED STATES
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Non-covered Loans held-in-portfolio		6,651,358		6,624,417
UNITED STATES | Non-covered loans
Financing Receivable, Allowance for Credit Losses
Balance at beginning of period		62,190	72,078
Provision (reversal) for loan losses		10,371	12,615
Charge-offs		(9,219)	(14,951)
Recoveries		2,903	3,631
Balance at end of period		66,245	73,373
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Specific ALLL		4,236	3,691
General ALLL		62,009	69,682
Ending balance: loans individually evaluated for impairment		32,176	14,926
Ending balance: loans collectively evaluated for impairment		6,619,182	6,333,331
Non-covered Loans held-in-portfolio		6,651,358	6,348,257
Commercial
Financing Receivable, Allowance for Credit Losses
Balance at beginning of period		239,115	215,665
Provision (reversal) for loan losses		4,802	31,489
Charge-offs		(22,942)	(15,185)
Recoveries		3,514	4,412
Balance at end of period		224,489	236,381
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Specific ALLL		33,476	45,028
General ALLL		191,013	191,353
Ending balance: loans individually evaluated for impairment		383,494	352,064
Ending balance: loans collectively evaluated for impairment		11,674,816	11,116,443
Non-covered Loans held-in-portfolio		12,058,310		12,043,019
Loans And Leases Receivable Covered And Not Covered Total Net Of Unearned Income		12,058,310	11,468,507
Commercial | PUERTO RICO
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Non-covered Loans held-in-portfolio		7,391,122		7,372,643
Commercial | PUERTO RICO | Non-covered loans
Financing Receivable, Allowance for Credit Losses
Balance at beginning of period		207,214	171,531
Provision (reversal) for loan losses		(1,689)	20,934
Charge-offs		(19,461)	(6,789)
Recoveries		2,867	2,846
Balance at end of period		188,931	188,522
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Specific ALLL		33,253	45,028
General ALLL		155,678	143,494
Ending balance: loans individually evaluated for impairment		381,803	352,064
Ending balance: loans collectively evaluated for impairment		7,009,319	6,770,732
Non-covered Loans held-in-portfolio		7,391,122	7,122,796
Commercial | PUERTO RICO | Covered loans
Financing Receivable, Allowance for Credit Losses
Balance at beginning of period			0
Provision (reversal) for loan losses			0
Charge-offs			0
Recoveries			0
Balance at end of period			0
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Specific ALLL			0
General ALLL			0
Ending balance: loans individually evaluated for impairment			0
Ending balance: loans collectively evaluated for impairment			0
Loans covered under loss-sharing agreements with the FDIC			0
Commercial | UNITED STATES
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Non-covered Loans held-in-portfolio		4,667,188		4,670,376
Commercial | UNITED STATES | Non-covered loans
Financing Receivable, Allowance for Credit Losses
Balance at beginning of period		31,901	44,134
Provision (reversal) for loan losses		6,491	10,555
Charge-offs		(3,481)	(8,396)
Recoveries		647	1,566
Balance at end of period		35,558	47,859
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Specific ALLL		223	0
General ALLL		35,335	47,859
Ending balance: loans individually evaluated for impairment		1,691	0
Ending balance: loans collectively evaluated for impairment		4,665,497	4,345,711
Non-covered Loans held-in-portfolio		4,667,188	4,345,711
Construction
Financing Receivable, Allowance for Credit Losses
Balance at beginning of period		7,424	8,362
Provision (reversal) for loan losses		47	1,179
Charge-offs		(22)	48
Recoveries		47	160
Balance at end of period		7,496	9,749
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Specific ALLL		19	474
General ALLL		7,477	9,275
Ending balance: loans individually evaluated for impairment		13,848	4,293
Ending balance: loans collectively evaluated for impairment		777,472	889,098
Non-covered Loans held-in-portfolio		791,320		779,449
Loans And Leases Receivable Covered And Not Covered Total Net Of Unearned Income		791,320	893,391
Construction | PUERTO RICO
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Non-covered Loans held-in-portfolio		91,372		85,955
Construction | PUERTO RICO | Non-covered loans
Financing Receivable, Allowance for Credit Losses
Balance at beginning of period		886	1,286
Provision (reversal) for loan losses		(81)	1,163
Charge-offs		(22)	48
Recoveries		39	160
Balance at end of period		822	2,657
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Specific ALLL		19	474
General ALLL		803	2,183
Ending balance: loans individually evaluated for impairment		1,788	4,293
Ending balance: loans collectively evaluated for impairment		89,584	89,565
Non-covered Loans held-in-portfolio		91,372	93,858
Construction | PUERTO RICO | Covered loans
Financing Receivable, Allowance for Credit Losses
Balance at beginning of period			0
Provision (reversal) for loan losses			0
Charge-offs			0
Recoveries			0
Balance at end of period			0
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Specific ALLL			0
General ALLL			0
Ending balance: loans individually evaluated for impairment			0
Ending balance: loans collectively evaluated for impairment			0
Loans covered under loss-sharing agreements with the FDIC			0
Construction | UNITED STATES
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Non-covered Loans held-in-portfolio		699,948		693,494
Construction | UNITED STATES | Non-covered loans
Financing Receivable, Allowance for Credit Losses
Balance at beginning of period		6,538	7,076
Provision (reversal) for loan losses		128	16
Charge-offs		0	0
Recoveries		8	0
Balance at end of period		6,674	7,092
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Specific ALLL		0	0
General ALLL		6,674	7,092
Ending balance: loans individually evaluated for impairment		12,060	0
Ending balance: loans collectively evaluated for impairment		687,888	799,533
Non-covered Loans held-in-portfolio		699,948	799,533
Mortgages
Financing Receivable, Allowance for Credit Losses
Balance at beginning of period		147,412	196,143
Provision (reversal) for loan losses		6,298	9,611
Charge-offs		(13,425)	(15,319)
Recoveries		2,013	1,015
Balance at end of period		142,298	191,450
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Specific ALLL		43,139	46,915
General ALLL		99,159	144,535
Ending balance: loans individually evaluated for impairment		524,803	519,922
Ending balance: loans collectively evaluated for impairment		6,682,377	7,045,405
Non-covered Loans held-in-portfolio		7,207,180		7,235,258
Loans And Leases Receivable Covered And Not Covered Total Net Of Unearned Income		7,207,180	7,565,327
Mortgages | PUERTO RICO
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Non-covered Loans held-in-portfolio		6,375,588		6,433,323
Mortgages | PUERTO RICO | Non-covered loans
Financing Receivable, Allowance for Credit Losses
Balance at beginning of period		142,978	159,081
Provision (reversal) for loan losses		6,061	7,464
Charge-offs		(13,174)	(13,791)
Recoveries		1,991	547
Balance at end of period		137,856	153,301
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Specific ALLL		40,779	44,419
General ALLL		97,077	108,882
Ending balance: loans individually evaluated for impairment		515,365	510,849
Ending balance: loans collectively evaluated for impairment		5,860,223	5,844,857
Non-covered Loans held-in-portfolio		6,375,588	6,355,706
Mortgages | PUERTO RICO | Covered loans
Financing Receivable, Allowance for Credit Losses
Balance at beginning of period			32,521
Provision (reversal) for loan losses			2,265
Charge-offs			(1,446)
Recoveries			82
Balance at end of period			33,422
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Specific ALLL			0
General ALLL			33,422
Ending balance: loans individually evaluated for impairment			0
Ending balance: loans collectively evaluated for impairment			500,683
Loans covered under loss-sharing agreements with the FDIC			500,683
Mortgages | UNITED STATES
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Non-covered Loans held-in-portfolio		831,592		801,935
Mortgages | UNITED STATES | Non-covered loans
Financing Receivable, Allowance for Credit Losses
Balance at beginning of period		4,434	4,541
Provision (reversal) for loan losses		237	(118)
Charge-offs		(251)	(82)
Recoveries		22	386
Balance at end of period		4,442	4,727
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Specific ALLL		2,360	2,496
General ALLL		2,082	2,231
Ending balance: loans individually evaluated for impairment		9,438	9,073
Ending balance: loans collectively evaluated for impairment		822,154	699,865
Non-covered Loans held-in-portfolio		831,592	708,938
Legacy
Financing Receivable, Allowance for Credit Losses
Balance at beginning of period		969	798
Provision (reversal) for loan losses		(855)	(477)
Charge-offs		164	(157)
Recoveries		551	488
Balance at end of period		829	652
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Specific ALLL		0	0
General ALLL		829	652
Ending balance: loans individually evaluated for impairment		0	0
Ending balance: loans collectively evaluated for impairment		24,404	31,167
Non-covered Loans held-in-portfolio	[1]	24,404		25,949
Loans And Leases Receivable Covered And Not Covered Total Net Of Unearned Income		24,404	31,167
Legacy | UNITED STATES
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Non-covered Loans held-in-portfolio		24,404		25,949
Legacy | UNITED STATES | Non-covered loans
Financing Receivable, Allowance for Credit Losses
Balance at beginning of period		969	798
Provision (reversal) for loan losses		(855)	(477)
Charge-offs		164	(157)
Recoveries		551	488
Balance at end of period		829	652
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Specific ALLL		0	0
General ALLL		829	652
Ending balance: loans individually evaluated for impairment		0	0
Ending balance: loans collectively evaluated for impairment		24,404	31,167
Non-covered Loans held-in-portfolio		24,404	31,167
Leasing
Financing Receivable, Allowance for Credit Losses
Balance at beginning of period		11,486	11,991
Provision (reversal) for loan losses		(891)	2,914
Charge-offs		(2,096)	(2,513)
Recoveries		610	520
Balance at end of period		9,109	12,912
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Specific ALLL		321	448
General ALLL		8,788	12,464
Ending balance: loans individually evaluated for impairment		1,018	1,361
Ending balance: loans collectively evaluated for impairment		962,214	837,022
Non-covered Loans held-in-portfolio		963,232		934,773
Loans And Leases Receivable Covered And Not Covered Total Net Of Unearned Income		963,232	838,383
Leasing | PUERTO RICO
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Non-covered Loans held-in-portfolio		963,232		934,773
Leasing | PUERTO RICO | Non-covered loans
Financing Receivable, Allowance for Credit Losses
Balance at beginning of period		11,486	11,991
Provision (reversal) for loan losses		(891)	2,914
Charge-offs		(2,096)	(2,513)
Recoveries		610	520
Balance at end of period		9,109	12,912
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Specific ALLL		321	448
General ALLL		8,788	12,464
Ending balance: loans individually evaluated for impairment		1,018	1,361
Ending balance: loans collectively evaluated for impairment		962,214	837,022
Non-covered Loans held-in-portfolio		963,232	838,383
Leasing | PUERTO RICO | Covered loans
Financing Receivable, Allowance for Credit Losses
Balance at beginning of period			0
Provision (reversal) for loan losses			0
Charge-offs			0
Recoveries			0
Balance at end of period			0
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Specific ALLL			0
General ALLL			0
Ending balance: loans individually evaluated for impairment			0
Ending balance: loans collectively evaluated for impairment			0
Loans covered under loss-sharing agreements with the FDIC			0
Consumer
Financing Receivable, Allowance for Credit Losses
Balance at beginning of period		162,942	190,467
Provision (reversal) for loan losses		32,424	26,347
Charge-offs		(41,520)	(34,690)
Recoveries		12,561	7,310
Balance at end of period		166,407	189,434
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Specific ALLL		25,003	24,150
General ALLL		141,404	165,284
Ending balance: loans individually evaluated for impairment		110,874	103,583
Ending balance: loans collectively evaluated for impairment		5,492,388	3,702,190
Non-covered Loans held-in-portfolio		5,603,262		5,489,441
Loans And Leases Receivable Covered And Not Covered Total Net Of Unearned Income		5,603,262	3,805,773
Consumer | PUERTO RICO
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Non-covered Loans held-in-portfolio		5,175,036		5,056,778
Consumer | PUERTO RICO | Non-covered loans
Financing Receivable, Allowance for Credit Losses
Balance at beginning of period		144,594	174,215
Provision (reversal) for loan losses		28,054	24,243
Charge-offs		(35,869)	(28,372)
Recoveries		10,886	6,117
Balance at end of period		147,665	176,203
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Specific ALLL		23,350	22,955
General ALLL		124,315	153,248
Ending balance: loans individually evaluated for impairment		101,887	97,730
Ending balance: loans collectively evaluated for impairment		5,073,149	3,231,207
Non-covered Loans held-in-portfolio		5,175,036	3,328,937
Consumer | PUERTO RICO | Covered loans
Financing Receivable, Allowance for Credit Losses
Balance at beginning of period			723
Provision (reversal) for loan losses			(535)
Charge-offs			(2)
Recoveries			2
Balance at end of period			188
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Specific ALLL			0
General ALLL			188
Ending balance: loans individually evaluated for impairment			0
Ending balance: loans collectively evaluated for impairment			13,928
Loans covered under loss-sharing agreements with the FDIC			13,928
Consumer | UNITED STATES
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Non-covered Loans held-in-portfolio		428,226		$ 432,663
Consumer | UNITED STATES | Non-covered loans
Financing Receivable, Allowance for Credit Losses
Balance at beginning of period		18,348	15,529
Provision (reversal) for loan losses		4,370	2,639
Charge-offs		(5,651)	(6,316)
Recoveries		1,675	1,191
Balance at end of period		18,742	13,043
Financing Receivable Allowance For Credit Loss Additional Information Abstract
Specific ALLL		1,653	1,195
General ALLL		17,089	11,848
Ending balance: loans individually evaluated for impairment		8,987	5,853
Ending balance: loans collectively evaluated for impairment		419,239	457,055
Non-covered Loans held-in-portfolio		$ 428,226	$ 462,908

[1] The legacy portfolio is comprised of commercial loans, construction loans and lease financings related to certain lending products exited by the Corporation as part of restructuring efforts carried out in prior years at the Popular U.S. segment.