Note Commitments and Contingencies (Schedule of Direct Exposure to Puerto Rico Government by Maturity) (Detail) - PR Government Direct Exposure - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Total concentration of risk	$ 519,679	$ 584,491
From PR Central Government
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Total concentration of risk	14,617
From Government Development Bank
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Total concentration of risk	1
From Public Corporation - Puerto Rico Highways And Transportation Authority
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Total concentration of risk	4
From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Total concentration of risk	505,057
Outstanding Balance
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	516,229	529,339
Outstanding Balance | From PR Central Government
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	14,617
Outstanding Balance | From Government Development Bank
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	1
Outstanding Balance | From Public Corporation - Puerto Rico Highways And Transportation Authority
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	4
Outstanding Balance | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	501,607	511,894
Loans Member | Outstanding Balance
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	450,617	458,794
Loans Member | Outstanding Balance | From PR Central Government
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	0
Loans Member | Outstanding Balance | From Government Development Bank
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	0
Loans Member | Outstanding Balance | From Public Corporation - Puerto Rico Highways And Transportation Authority
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	0
Loans Member | Outstanding Balance | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	450,617
Securities Investment Member | Outstanding Balance
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	65,612	$ 70,545
Securities Investment Member | Outstanding Balance | From PR Central Government
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	14,617
Securities Investment Member | Outstanding Balance | From Government Development Bank
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	1
Securities Investment Member | Outstanding Balance | From Public Corporation - Puerto Rico Highways And Transportation Authority
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	4
Securities Investment Member | Outstanding Balance | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	50,990
Within 1 year | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Total concentration of risk	25,659
Within 1 year | Outstanding Balance | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	22,209
Within 1 year | Loans Member | Outstanding Balance | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	18,974
Within 1 year | Securities Investment Member | Outstanding Balance | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	3,235
After 1 and within 5 years | From Government Development Bank
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Total concentration of risk	1
After 1 and within 5 years | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Total concentration of risk	143,208
After 1 and within 5 years | Outstanding Balance | From Government Development Bank
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	1
After 1 and within 5 years | Outstanding Balance | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	143,208
After 1 and within 5 years | Loans Member | Outstanding Balance | From Government Development Bank
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	0
After 1 and within 5 years | Loans Member | Outstanding Balance | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	128,008
After 1 and within 5 years | Securities Investment Member | Outstanding Balance | From Government Development Bank
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	1
After 1 and within 5 years | Securities Investment Member | Outstanding Balance | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	15,200
After 5 to 10 years | From PR Central Government
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Total concentration of risk	3,054
After 5 to 10 years | From Public Corporation - Puerto Rico Highways And Transportation Authority
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Total concentration of risk	4
After 5 to 10 years | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Total concentration of risk	162,460
After 5 to 10 years | Outstanding Balance | From PR Central Government
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	3,054
After 5 to 10 years | Outstanding Balance | From Public Corporation - Puerto Rico Highways And Transportation Authority
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	4
After 5 to 10 years | Outstanding Balance | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	162,460
After 5 to 10 years | Loans Member | Outstanding Balance | From PR Central Government
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	0
After 5 to 10 years | Loans Member | Outstanding Balance | From Public Corporation - Puerto Rico Highways And Transportation Authority
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	0
After 5 to 10 years | Loans Member | Outstanding Balance | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	144,975
After 5 to 10 years | Securities Investment Member | Outstanding Balance | From PR Central Government
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	3,054
After 5 to 10 years | Securities Investment Member | Outstanding Balance | From Public Corporation - Puerto Rico Highways And Transportation Authority
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	4
After 5 to 10 years | Securities Investment Member | Outstanding Balance | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	17,485
After 10 years | From PR Central Government
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Total concentration of risk	11,563
After 10 years | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Total concentration of risk	173,730
After 10 years | Outstanding Balance | From PR Central Government
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	11,563
After 10 years | Outstanding Balance | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	173,730
After 10 years | Loans Member | Outstanding Balance | From PR Central Government
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	0
After 10 years | Loans Member | Outstanding Balance | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	158,660
After 10 years | Securities Investment Member | Outstanding Balance | From PR Central Government
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	11,563
After 10 years | Securities Investment Member | Outstanding Balance | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	$ 15,070