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
	Mar. 31, 2019	Dec. 31, 2018
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	$ 455,525	$ 457,988
Total concentration of risk	455,525
From PR Central Government
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	62
Total concentration of risk	62
From Government Development Bank
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	3
Total concentration of risk	3
From Public Corporation - Puerto Rico Highways And Transportation Authority
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	5
Total concentration of risk	5
From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	455,455
Total concentration of risk	455,455
Loans
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	413,100	413,165
Loans | From PR Central Government
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	0
Loans | From Government Development Bank
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	0
Loans | 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 | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	413,100
Securities Investment
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	42,425	$ 44,823
Securities Investment | From PR Central Government
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	62
Securities Investment | From Government Development Bank
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	3
Securities Investment | From Public Corporation - Puerto Rico Highways And Transportation Authority
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	5
Securities Investment | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	42,355
Within 1 year | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	18,935
Total concentration of risk	18,935
Within 1 year | Loans | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	15,265
Within 1 year | Securities Investment | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	3,670
After 1 and within 5 years | From PR Central Government
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	6
Total concentration of risk	6
After 1 and within 5 years | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	215,242
Total concentration of risk	215,242
After 1 and within 5 years | Loans | From PR Central Government
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	0
After 1 and within 5 years | Loans | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	197,987
After 1 and within 5 years | Securities Investment | From PR Central Government
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	6
After 1 and within 5 years | Securities Investment | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	17,255
After 5 to 10 years | From PR Central Government
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	28
Total concentration of risk	28
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]
Outstanding concentration of risk	5
Total concentration of risk	5
After 5 to 10 years | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	122,248
Total concentration of risk	122,248
After 5 to 10 years | Loans | 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 | 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 | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	101,663
After 5 to 10 years | Securities Investment | From PR Central Government
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	28
After 5 to 10 years | Securities Investment | From Public Corporation - Puerto Rico Highways And Transportation Authority
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	5
After 5 to 10 years | Securities Investment | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	20,585
After 10 years | From PR Central Government
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	28
Total concentration of risk	28
After 10 years | From Government Development Bank
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	3
Total concentration of risk	3
After 10 years | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	99,030
Total concentration of risk	99,030
After 10 years | Loans | From PR Central Government
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	0
After 10 years | Loans | From Government Development Bank
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	0
After 10 years | Loans | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	98,185
After 10 years | Securities Investment | From PR Central Government
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	28
After 10 years | Securities Investment | From Government Development Bank
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	3
After 10 years | Securities Investment | From Municipalities
Direct Exposure To The Puerto Rico Government By Maturity [Line Items]
Outstanding concentration of risk	$ 845