Note Allowance for loan losses (Average recorded investment and interest income recognized on impaired loans) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	$ 963,138	$ 930,221
Interest Income Recognized	6,884	6,476
Commercial multi-family | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	81
Interest Income Recognized	1
CRE non-owner occupied | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	118,836	118,660
Interest Income Recognized	1,375	1,159
CRE owner occupied | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	164,512	158,046
Interest Income Recognized	1,598	1,393
Commercial and industrial | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	60,195	61,351
Interest Income Recognized	497	516
Construction | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment		2,251
Interest Income Recognized		21
Mortgages | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	508,467	475,512
Interest Income Recognized	3,413	3,387
Leasing | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	1,810	2,398
Interest Income Recognized	0	0
Consumer | Credit cards | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	37,708	38,256
Interest Income Recognized	0	0
Consumer | Home equity lines of credit | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	2,693	1,599
Interest Income Recognized	0	0
Consumer | Personal | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	65,950	68,785
Interest Income Recognized	0	0
Consumer | Auto | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	2,094	2,878
Interest Income Recognized	0	0
Consumer | Other | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	792	485
Interest Income Recognized	0	0
PUERTO RICO
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	951,429	920,647
Interest Income Recognized	6,840	6,476
PUERTO RICO | Commercial multi-family | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	81
Interest Income Recognized	1
PUERTO RICO | CRE non-owner occupied | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	118,836	118,660
Interest Income Recognized	1,375	1,159
PUERTO RICO | CRE owner occupied | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	164,512	158,046
Interest Income Recognized	1,598	1,393
PUERTO RICO | Commercial and industrial | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	60,195	61,351
Interest Income Recognized	497	516
PUERTO RICO | Construction | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment		2,251
Interest Income Recognized		21
PUERTO RICO | Mortgages | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	499,568	468,150
Interest Income Recognized	3,369	3,387
PUERTO RICO | Leasing | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	1,810	2,398
Interest Income Recognized	0	0
PUERTO RICO | Consumer | Credit cards | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	37,708	38,256
Interest Income Recognized	0	0
PUERTO RICO | Consumer | Home equity lines of credit | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	0	0
Interest Income Recognized	0	0
PUERTO RICO | Consumer | Personal | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	65,833	68,172
Interest Income Recognized	0	0
PUERTO RICO | Consumer | Auto | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	2,094	2,878
Interest Income Recognized	0	0
PUERTO RICO | Consumer | Other | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	792	485
Interest Income Recognized	0	0
UNITED STATES
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	11,709	9,574
Interest Income Recognized	44	0
UNITED STATES | Commercial multi-family | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	0
Interest Income Recognized	0
UNITED STATES | CRE non-owner occupied | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	0	0
Interest Income Recognized	0	0
UNITED STATES | CRE owner occupied | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	0	0
Interest Income Recognized	0	0
UNITED STATES | Commercial and industrial | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	0	0
Interest Income Recognized	0	0
UNITED STATES | Construction | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment		0
Interest Income Recognized		0
UNITED STATES | Mortgages | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	8,899	7,362
Interest Income Recognized	44	0
UNITED STATES | Leasing | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	0	0
Interest Income Recognized	0	0
UNITED STATES | Consumer | Credit cards | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	0	0
Interest Income Recognized	0	0
UNITED STATES | Consumer | Home equity lines of credit | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	2,693	1,599
Interest Income Recognized	0	0
UNITED STATES | Consumer | Personal | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	117	613
Interest Income Recognized	0	0
UNITED STATES | Consumer | Auto | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	0	0
Interest Income Recognized	0	0
UNITED STATES | Consumer | Other | Non Covered Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	0	0
Interest Income Recognized	$ 0	$ 0