Note Allowance for loan losses (Disclosures related to loans individually evaluated for impairment) (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Financing Receivable, Impaired
Related Allowance	$ 124,037	$ 118,072
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	128,599	118,406
Impaired Financing Receivable, with Related Allowance, Recorded Investment	806,051	807,380
Recorded Investment	934,650	925,786
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	175,233	170,520
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	878,324	881,819
Unpaid Principal Balance	1,053,557	1,052,339
PUERTO RICO
Financing Receivable, Impaired
Related Allowance	121,864	116,523
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	124,668	114,870
Impaired Financing Receivable, with Related Allowance, Recorded Investment	799,826	801,925
Recorded Investment	924,494	916,795
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	170,534	166,082
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	871,386	875,471
Unpaid Principal Balance	1,041,920	1,041,553
UNITED STATES | Non Covered Loans
Financing Receivable, Impaired
Related Allowance	2,173	1,549
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	3,931	3,536
Impaired Financing Receivable, with Related Allowance, Recorded Investment	6,225	5,455
Recorded Investment	10,156	8,991
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	4,699	4,438
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	6,938	6,348
Unpaid Principal Balance	11,637	10,786
CRE non-owner occupied | Non Covered Loans
Financing Receivable, Impaired
Related Allowance	37,638	30,980
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	13,636	13,779
Impaired Financing Receivable, with Related Allowance, Recorded Investment	107,706	102,199
Recorded Investment	121,342	115,978
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	23,754	23,896
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	112,100	106,466
Unpaid Principal Balance	135,854	130,362
CRE non-owner occupied | PUERTO RICO | Non Covered Loans
Financing Receivable, Impaired
Related Allowance	37,638	30,980
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	13,636	13,779
Impaired Financing Receivable, with Related Allowance, Recorded Investment	107,706	102,199
Recorded Investment	121,342	115,978
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	23,754	23,896
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	112,100	106,466
Unpaid Principal Balance	135,854	130,362
CRE owner occupied | Non Covered Loans
Financing Receivable, Impaired
Related Allowance	10,888	12,564
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	38,763	38,955
Impaired Financing Receivable, with Related Allowance, Recorded Investment	120,121	118,253
Recorded Investment	158,884	157,208
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	63,165	63,383
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	139,841	137,193
Unpaid Principal Balance	203,006	200,576
CRE owner occupied | PUERTO RICO | Non Covered Loans
Financing Receivable, Impaired
Related Allowance	10,888	12,564
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	38,763	38,955
Impaired Financing Receivable, with Related Allowance, Recorded Investment	120,121	118,253
Recorded Investment	158,884	157,208
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	63,165	63,383
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	139,841	137,193
Unpaid Principal Balance	203,006	200,576
Commercial and industrial | Non Covered Loans
Financing Receivable, Impaired
Related Allowance	6,572	5,699
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	19,407	21,904
Impaired Financing Receivable, with Related Allowance, Recorded Investment	39,347	42,043
Recorded Investment	58,754	63,947
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	21,525	32,922
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	40,849	43,629
Unpaid Principal Balance	62,374	76,551
Commercial and industrial | PUERTO RICO | Non Covered Loans
Financing Receivable, Impaired
Related Allowance	6,572	5,699
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	19,407	21,904
Impaired Financing Receivable, with Related Allowance, Recorded Investment	39,347	42,043
Recorded Investment	58,754	63,947
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	21,525	32,922
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	40,849	43,629
Unpaid Principal Balance	62,374	76,551
Construction | Non Covered Loans
Financing Receivable, Impaired
Related Allowance	172	264
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	2,020	2,481
Recorded Investment	2,020	2,481
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	0	0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	5,472	7,878
Unpaid Principal Balance	5,472	7,878
Construction | PUERTO RICO | Non Covered Loans
Financing Receivable, Impaired
Related Allowance	172	264
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	2,020	2,481
Recorded Investment	2,020	2,481
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	0	0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	5,472	7,878
Unpaid Principal Balance	5,472	7,878
Mortgages | Non Covered Loans
Financing Receivable, Impaired
Related Allowance	43,252	44,029
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	55,997	42,904
Impaired Financing Receivable, with Related Allowance, Recorded Investment	423,095	429,028
Recorded Investment	479,092	471,932
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	65,993	49,455
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	466,300	473,258
Unpaid Principal Balance	532,293	522,713
Mortgages | PUERTO RICO | Non Covered Loans
Financing Receivable, Impaired
Related Allowance	41,660	42,965
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	52,862	40,232
Impaired Financing Receivable, with Related Allowance, Recorded Investment	418,321	424,885
Recorded Investment	471,183	465,117
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	62,090	45,881
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	460,813	468,240
Unpaid Principal Balance	522,903	514,121
Mortgages | UNITED STATES | Non Covered Loans
Financing Receivable, Impaired
Related Allowance	1,592	1,064
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	3,135	2,672
Impaired Financing Receivable, with Related Allowance, Recorded Investment	4,774	4,143
Recorded Investment	7,909	6,815
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	3,903	3,574
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	5,487	5,018
Unpaid Principal Balance	9,390	8,592
Leasing | Non Covered Loans
Financing Receivable, Impaired
Related Allowance	608	573
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	2,391	2,404
Recorded Investment	2,391	2,404
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	0	0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	2,391	2,404
Unpaid Principal Balance	2,391	2,404
Leasing | PUERTO RICO | Non Covered Loans
Financing Receivable, Impaired
Related Allowance	608	573
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	2,391	2,404
Recorded Investment	2,391	2,404
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	0	0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	2,391	2,404
Unpaid Principal Balance	2,391	2,404
Consumer | Credit cards | Non Covered Loans
Financing Receivable, Impaired
Related Allowance	5,963	6,675
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	37,778	38,734
Recorded Investment	37,778	38,734
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	0	0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	37,778	38,734
Unpaid Principal Balance	37,778	38,734
Consumer | Credit cards | PUERTO RICO | Non Covered Loans
Financing Receivable, Impaired
Related Allowance	5,963	6,675
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	37,778	38,734
Recorded Investment	37,778	38,734
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	0	0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	37,778	38,734
Unpaid Principal Balance	37,778	38,734
Consumer | Home equity lines of credit | Non Covered Loans
Financing Receivable, Impaired
Related Allowance	352	259
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	715	783
Impaired Financing Receivable, with Related Allowance, Recorded Investment	921	778
Recorded Investment	1,636	1,561
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	715	783
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	921	796
Unpaid Principal Balance	1,636	1,579
Consumer | Home equity lines of credit | UNITED STATES | Non Covered Loans
Financing Receivable, Impaired
Related Allowance	352	259
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	715	783
Impaired Financing Receivable, with Related Allowance, Recorded Investment	921	778
Recorded Investment	1,636	1,561
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	715	783
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	921	796
Unpaid Principal Balance	1,636	1,579
Consumer | Personal | Non Covered Loans
Financing Receivable, Impaired
Related Allowance	17,746	16,591
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	81	81
Impaired Financing Receivable, with Related Allowance, Recorded Investment	68,364	69,043
Recorded Investment	68,445	69,124
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	81	81
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	68,364	69,043
Unpaid Principal Balance	68,445	69,124
Consumer | Personal | PUERTO RICO | Non Covered Loans
Financing Receivable, Impaired
Related Allowance	17,517	16,365
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	67,834	68,509
Recorded Investment	67,834	68,509
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	0	0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	67,834	68,509
Unpaid Principal Balance	67,834	68,509
Consumer | Personal | UNITED STATES | Non Covered Loans
Financing Receivable, Impaired
Related Allowance	229	226
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	81	81
Impaired Financing Receivable, with Related Allowance, Recorded Investment	530	534
Recorded Investment	611	615
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	81	81
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	530	534
Unpaid Principal Balance	611	615
Consumer | Auto | Non Covered Loans
Financing Receivable, Impaired
Related Allowance	771	338
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	3,863	1,893
Recorded Investment	3,863	1,893
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	0	0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	3,863	1,893
Unpaid Principal Balance	3,863	1,893
Consumer | Auto | PUERTO RICO | Non Covered Loans
Financing Receivable, Impaired
Related Allowance	771	338
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	3,863	1,893
Recorded Investment	3,863	1,893
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	0	0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	3,863	1,893
Unpaid Principal Balance	3,863	1,893
Consumer | Other | Non Covered Loans
Financing Receivable, Impaired
Related Allowance	75	100
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	445	524
Recorded Investment	445	524
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	0	0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	445	525
Unpaid Principal Balance	445	525
Consumer | Other | PUERTO RICO | Non Covered Loans
Financing Receivable, Impaired
Related Allowance	75	100
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	445	524
Recorded Investment	445	524
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	0	0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	445	525
Unpaid Principal Balance	$ 445	$ 525