Note Allowance for loan losses (Disclosures related to loans individually evaluated for impairment) (Detail) - Non Covered Loans - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Financing Receivable, Impaired
Related Allowance	$ 101,958	$ 119,670
Impaired Financing Receivable, Recorded Investment [Abstract]
Recorded investment - with an Allowance	777,380	795,308
Recorded investment - with No Allowance	256,657	249,787
Recorded Investment - Total	1,034,037	1,045,095
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Unpaid principal balance - with an Allowance	864,585	867,932
Unpaid principal balance - with No Allowance	387,290	377,884
Unpaid Principal Balance - Total	1,251,875	1,245,816
Commercial multi-family
Financing Receivable, Impaired
Related Allowance	4	4
Impaired Financing Receivable, Recorded Investment [Abstract]
Recorded investment - with an Allowance	924	932
Recorded investment - with No Allowance	0	0
Recorded Investment - Total	924	932
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Unpaid principal balance - with an Allowance	924	932
Unpaid principal balance - with No Allowance	0	0
Unpaid Principal Balance - Total	924	932
CRE non-owner occupied
Financing Receivable, Impaired
Related Allowance	22,536	27,494
Impaired Financing Receivable, Recorded Investment [Abstract]
Recorded investment - with an Allowance	72,891	85,583
Recorded investment - with No Allowance	102,971	96,005
Recorded Investment - Total	175,862	181,588
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Unpaid principal balance - with an Allowance	73,589	86,282
Unpaid principal balance - with No Allowance	149,106	138,378
Unpaid Principal Balance - Total	222,695	224,660
CRE owner occupied
Financing Receivable, Impaired
Related Allowance	7,685	7,857
Impaired Financing Receivable, Recorded Investment [Abstract]
Recorded investment - with an Allowance	114,017	113,592
Recorded investment - with No Allowance	27,300	26,474
Recorded Investment - Total	141,317	140,066
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Unpaid principal balance - with an Allowance	133,506	132,677
Unpaid principal balance - with No Allowance	59,652	60,485
Unpaid Principal Balance - Total	193,158	193,162
Commercial and industrial
Financing Receivable, Impaired
Related Allowance	3,251	16,835
Impaired Financing Receivable, Recorded Investment [Abstract]
Recorded investment - with an Allowance	55,496	65,208
Recorded investment - with No Allowance	9,895	10,724
Recorded Investment - Total	65,391	75,932
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Unpaid principal balance - with an Allowance	68,923	67,094
Unpaid principal balance - with No Allowance	20,139	20,968
Unpaid Principal Balance - Total	89,062	88,062
Construction
Financing Receivable, Impaired
Related Allowance	19	56
Impaired Financing Receivable, Recorded Investment [Abstract]
Recorded investment - with an Allowance	1,788	1,788
Recorded investment - with No Allowance	12,060	12,060
Recorded Investment - Total	13,848	13,848
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Unpaid principal balance - with an Allowance	1,788	1,788
Unpaid principal balance - with No Allowance	18,127	18,127
Unpaid Principal Balance - Total	19,915	19,915
Mortgages
Financing Receivable, Impaired
Related Allowance	43,139	41,211
Impaired Financing Receivable, Recorded Investment [Abstract]
Recorded investment - with an Allowance	421,898	416,004
Recorded investment - with No Allowance	102,905	102,884
Recorded Investment - Total	524,803	518,888
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Unpaid principal balance - with an Allowance	475,404	466,909
Unpaid principal balance - with No Allowance	138,583	138,211
Unpaid Principal Balance - Total	613,987	605,120
Leasing
Financing Receivable, Impaired
Related Allowance	321	320
Impaired Financing Receivable, Recorded Investment [Abstract]
Recorded investment - with an Allowance	1,018	1,099
Recorded investment - with No Allowance	0	0
Recorded Investment - Total	1,018	1,099
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Unpaid principal balance - with an Allowance	1,018	1,099
Unpaid principal balance - with No Allowance	0	0
Unpaid Principal Balance - Total	1,018	1,099
Consumer | Credit cards
Financing Receivable, Impaired
Related Allowance	4,200	4,571
Impaired Financing Receivable, Recorded Investment [Abstract]
Recorded investment - with an Allowance	27,879	28,829
Recorded investment - with No Allowance	0	0
Recorded Investment - Total	27,879	28,829
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Unpaid principal balance - with an Allowance	27,879	28,829
Unpaid principal balance - with No Allowance	0	0
Unpaid Principal Balance - Total	27,879	28,829
Consumer | Home equity lines of credit
Financing Receivable, Impaired
Related Allowance	1,393	1,558
Impaired Financing Receivable, Recorded Investment [Abstract]
Recorded investment - with an Allowance	6,830	6,236
Recorded investment - with No Allowance	1,358	1,498
Recorded Investment - Total	8,188	7,734
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Unpaid principal balance - with an Allowance	6,914	6,285
Unpaid principal balance - with No Allowance	1,452	1,572
Unpaid Principal Balance - Total	8,366	7,857
Consumer | Personal Loan
Financing Receivable, Impaired
Related Allowance	19,011	19,350
Impaired Financing Receivable, Recorded Investment [Abstract]
Recorded investment - with an Allowance	72,238	73,620
Recorded investment - with No Allowance	168	142
Recorded Investment - Total	72,406	73,762
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Unpaid principal balance - with an Allowance	72,239	73,620
Unpaid principal balance - with No Allowance	231	143
Unpaid Principal Balance - Total	72,470	73,763
Consumer | Auto Loan
Financing Receivable, Impaired
Related Allowance	229	228
Impaired Financing Receivable, Recorded Investment [Abstract]
Recorded investment - with an Allowance	1,163	1,161
Recorded investment - with No Allowance	0	0
Recorded Investment - Total	1,163	1,161
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Unpaid principal balance - with an Allowance	1,163	1,161
Unpaid principal balance - with No Allowance	0	0
Unpaid Principal Balance - Total	1,163	1,161
Consumer | Other
Financing Receivable, Impaired
Related Allowance	170	186
Impaired Financing Receivable, Recorded Investment [Abstract]
Recorded investment - with an Allowance	1,238	1,256
Recorded investment - with No Allowance	0	0
Recorded Investment - Total	1,238	1,256
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Unpaid principal balance - with an Allowance	1,238	1,256
Unpaid principal balance - with No Allowance	0	0
Unpaid Principal Balance - Total	1,238	1,256
PUERTO RICO
Financing Receivable, Impaired
Related Allowance	97,722	115,409
Impaired Financing Receivable, Recorded Investment [Abstract]
Recorded investment - with an Allowance	761,314	781,204
Recorded investment - with No Allowance	240,547	233,904
Recorded Investment - Total	1,001,861	1,015,108
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Unpaid principal balance - with an Allowance	846,800	852,117
Unpaid principal balance - with No Allowance	363,932	354,915
Unpaid Principal Balance - Total	1,210,732	1,207,032
PUERTO RICO | Commercial multi-family
Financing Receivable, Impaired
Related Allowance	4	4
Impaired Financing Receivable, Recorded Investment [Abstract]
Recorded investment - with an Allowance	924	932
Recorded investment - with No Allowance	0	0
Recorded Investment - Total	924	932
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Unpaid principal balance - with an Allowance	924	932
Unpaid principal balance - with No Allowance	0	0
Unpaid Principal Balance - Total	924	932
PUERTO RICO | CRE non-owner occupied
Financing Receivable, Impaired
Related Allowance	22,536	27,494
Impaired Financing Receivable, Recorded Investment [Abstract]
Recorded investment - with an Allowance	72,891	85,583
Recorded investment - with No Allowance	102,971	96,005
Recorded Investment - Total	175,862	181,588
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Unpaid principal balance - with an Allowance	73,589	86,282
Unpaid principal balance - with No Allowance	149,106	138,378
Unpaid Principal Balance - Total	222,695	224,660
PUERTO RICO | CRE owner occupied
Financing Receivable, Impaired
Related Allowance	7,462	7,857
Impaired Financing Receivable, Recorded Investment [Abstract]
Recorded investment - with an Allowance	112,326	113,592
Recorded investment - with No Allowance	27,300	26,474
Recorded Investment - Total	139,626	140,066
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Unpaid principal balance - with an Allowance	131,793	132,677
Unpaid principal balance - with No Allowance	59,652	60,485
Unpaid Principal Balance - Total	191,445	193,162
PUERTO RICO | Commercial and industrial
Financing Receivable, Impaired
Related Allowance	3,251	16,835
Impaired Financing Receivable, Recorded Investment [Abstract]
Recorded investment - with an Allowance	55,496	65,208
Recorded investment - with No Allowance	9,895	10,724
Recorded Investment - Total	65,391	75,932
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Unpaid principal balance - with an Allowance	68,923	67,094
Unpaid principal balance - with No Allowance	20,139	20,968
Unpaid Principal Balance - Total	89,062	88,062
PUERTO RICO | Construction
Financing Receivable, Impaired
Related Allowance	19	56
Impaired Financing Receivable, Recorded Investment [Abstract]
Recorded investment - with an Allowance	1,788	1,788
Recorded investment - with No Allowance	0	0
Recorded Investment - Total	1,788	1,788
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Unpaid principal balance - with an Allowance	1,788	1,788
Unpaid principal balance - with No Allowance	0	0
Unpaid Principal Balance - Total	1,788	1,788
PUERTO RICO | Mortgages
Financing Receivable, Impaired
Related Allowance	40,779	38,760
Impaired Financing Receivable, Recorded Investment [Abstract]
Recorded investment - with an Allowance	414,984	408,767
Recorded investment - with No Allowance	100,381	100,701
Recorded Investment - Total	515,365	509,468
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Unpaid principal balance - with an Allowance	466,878	458,010
Unpaid principal balance - with No Allowance	135,035	135,084
Unpaid Principal Balance - Total	601,913	593,094
PUERTO RICO | Leasing
Financing Receivable, Impaired
Related Allowance	321	320
Impaired Financing Receivable, Recorded Investment [Abstract]
Recorded investment - with an Allowance	1,018	1,099
Recorded investment - with No Allowance	0	0
Recorded Investment - Total	1,018	1,099
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Unpaid principal balance - with an Allowance	1,018	1,099
Unpaid principal balance - with No Allowance	0	0
Unpaid Principal Balance - Total	1,018	1,099
PUERTO RICO | Consumer | Credit cards
Financing Receivable, Impaired
Related Allowance	4,200	4,571
Impaired Financing Receivable, Recorded Investment [Abstract]
Recorded investment - with an Allowance	27,879	28,829
Recorded investment - with No Allowance	0	0
Recorded Investment - Total	27,879	28,829
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Unpaid principal balance - with an Allowance	27,879	28,829
Unpaid principal balance - with No Allowance	0	0
Unpaid Principal Balance - Total	27,879	28,829
PUERTO RICO | Consumer | Personal Loan
Financing Receivable, Impaired
Related Allowance	18,751	19,098
Impaired Financing Receivable, Recorded Investment [Abstract]
Recorded investment - with an Allowance	71,607	72,989
Recorded investment - with No Allowance	0	0
Recorded Investment - Total	71,607	72,989
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Unpaid principal balance - with an Allowance	71,607	72,989
Unpaid principal balance - with No Allowance	0	0
Unpaid Principal Balance - Total	71,607	72,989
PUERTO RICO | Consumer | Auto Loan
Financing Receivable, Impaired
Related Allowance	229	228
Impaired Financing Receivable, Recorded Investment [Abstract]
Recorded investment - with an Allowance	1,163	1,161
Recorded investment - with No Allowance	0	0
Recorded Investment - Total	1,163	1,161
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Unpaid principal balance - with an Allowance	1,163	1,161
Unpaid principal balance - with No Allowance	0	0
Unpaid Principal Balance - Total	1,163	1,161
PUERTO RICO | Consumer | Other
Financing Receivable, Impaired
Related Allowance	170	186
Impaired Financing Receivable, Recorded Investment [Abstract]
Recorded investment - with an Allowance	1,238	1,256
Recorded investment - with No Allowance	0	0
Recorded Investment - Total	1,238	1,256
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Unpaid principal balance - with an Allowance	1,238	1,256
Unpaid principal balance - with No Allowance	0	0
Unpaid Principal Balance - Total	1,238	1,256
UNITED STATES
Financing Receivable, Impaired
Related Allowance	4,236	4,261
Impaired Financing Receivable, Recorded Investment [Abstract]
Recorded investment - with an Allowance	16,066	14,104
Recorded investment - with No Allowance	16,110	15,883
Recorded Investment - Total	32,176	29,987
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Unpaid principal balance - with an Allowance	17,785	15,815
Unpaid principal balance - with No Allowance	23,358	22,969
Unpaid Principal Balance - Total	41,143	38,784
UNITED STATES | CRE owner occupied
Financing Receivable, Impaired
Related Allowance	223
Impaired Financing Receivable, Recorded Investment [Abstract]
Recorded investment - with an Allowance	1,691
Recorded investment - with No Allowance	0
Recorded Investment - Total	1,691
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Unpaid principal balance - with an Allowance	1,713
Unpaid principal balance - with No Allowance	0
Unpaid Principal Balance - Total	1,713
UNITED STATES | Construction
Financing Receivable, Impaired
Related Allowance	0	0
Impaired Financing Receivable, Recorded Investment [Abstract]
Recorded investment - with an Allowance	0	0
Recorded investment - with No Allowance	12,060	12,060
Recorded Investment - Total	12,060	12,060
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Unpaid principal balance - with an Allowance	0	0
Unpaid principal balance - with No Allowance	18,127	18,127
Unpaid Principal Balance - Total	18,127	18,127
UNITED STATES | Mortgages
Financing Receivable, Impaired
Related Allowance	2,360	2,451
Impaired Financing Receivable, Recorded Investment [Abstract]
Recorded investment - with an Allowance	6,914	7,237
Recorded investment - with No Allowance	2,524	2,183
Recorded Investment - Total	9,438	9,420
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Unpaid principal balance - with an Allowance	8,526	8,899
Unpaid principal balance - with No Allowance	3,548	3,127
Unpaid Principal Balance - Total	12,074	12,026
UNITED STATES | Consumer | Home equity lines of credit
Financing Receivable, Impaired
Related Allowance	1,393	1,558
Impaired Financing Receivable, Recorded Investment [Abstract]
Recorded investment - with an Allowance	6,830	6,236
Recorded investment - with No Allowance	1,358	1,498
Recorded Investment - Total	8,188	7,734
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Unpaid principal balance - with an Allowance	6,914	6,285
Unpaid principal balance - with No Allowance	1,452	1,572
Unpaid Principal Balance - Total	8,366	7,857
UNITED STATES | Consumer | Personal Loan
Financing Receivable, Impaired
Related Allowance	260	252
Impaired Financing Receivable, Recorded Investment [Abstract]
Recorded investment - with an Allowance	631	631
Recorded investment - with No Allowance	168	142
Recorded Investment - Total	799	773
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Unpaid principal balance - with an Allowance	632	631
Unpaid principal balance - with No Allowance	231	143
Unpaid Principal Balance - Total	$ 863	$ 774