Note Debt Securities Held-to-maturity (Amortized cost, gross unrealized gains and losses, approximate fair value, weighted average yield and contractual maturities of debt securities HTM) (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Amortized cost
Amortized Cost	$ 99,455	$ 101,575
Gross unrecognized gains
Gross Unrealized Gains	5,754	3,946
Gross unrealized losses
Gross Unrealized Losses	1,752	2,868
Fair Value
Total investment securities held-to-maturity - Fair Value	$ 103,457	$ 102,653
Weighted Average Yield
Weighted Average Yield	3.53%	3.60%
Obligations of Puerto Rico, States and political subdivisions
Amortized cost
Amortized cost - Within 1 year	$ 3,670	$ 3,510
Amortized cost - After 1 to 5 years	17,255	16,505
Amortized cost - After 5 to 10 years	20,585	23,885
Amortized cost - After 10 years	45,831	45,559
Amortized Cost	87,341	89,459
Gross unrecognized gains
Gross unrealized gains - Within 1 year	0	0
Gross unrealized gains - After 1 to 5 years	0	0
Gross unrealized gains - After 5 to 10 years	0	0
Gross unrealized gains - After 10 years	5,751	3,943
Gross Unrealized Gains	5,751	3,943
Gross unrealized losses
Gross unrealized losses - Within 1 year	31	36
Gross unrealized losses - After 1 to 5 years	205	1,081
Gross unrealized losses - After 5 to 10 years	1,502	1,704
Gross unrealized losses - After 10 years	14	47
Gross Unrealized Losses	1,752	2,868
Fair Value
Fair Value - within 1 year	3,639	3,474
Fair Value - After 1 to 5 years	17,050	15,424
Fair Value - After 5 to 10 years	19,083	22,181
Fair Value - After 10 years	51,568	49,455
Total investment securities held-to-maturity - Fair Value	$ 91,340	$ 90,534
Weighted Average Yield
Weighted average yield - Within 1 Year	6.01%	5.99%
Weighted average yield - After 1 to 5 years	6.10%	6.07%
Weighted average yield - After 5 to 10 years	3.19%	3.61%
Weighted average yield - After 10 years	1.76%	1.79%
Weighted Average Yield	3.13%	3.23%
Collateralized Mortgage Obligations - Federal agencies
Amortized cost
Amortized cost - After 5 to 10 years	$ 53	$ 55
Amortized Cost	53	55
Gross unrecognized gains
Gross unrealized gains - After 5 to 10 years	3	3
Gross Unrealized Gains	3	3
Gross unrealized losses
Gross unrealized losses - After 5 to 10 years	0	0
Gross Unrealized Losses	0	0
Fair Value
Fair Value - After 5 to 10 years	56	58
Total investment securities held-to-maturity - Fair Value	$ 56	$ 58
Weighted Average Yield
Weighted average yield - After 5 to 10 years	6.44%	5.45%
Weighted Average Yield	6.44%	5.45%
Securities in wholly owned statutory business trusts
Amortized cost
Amortized cost - After 10 years	$ 11,561	$ 11,561
Amortized Cost	11,561	11,561
Gross unrecognized gains
Gross unrealized gains - After 10 years	0	0
Gross Unrealized Gains	0	0
Gross unrealized losses
Gross unrealized losses - After 10 years	0	0
Gross Unrealized Losses	0	0
Fair Value
Fair Value - After 10 years	11,561	11,561
Total investment securities held-to-maturity - Fair Value	$ 11,561	$ 11,561
Weighted Average Yield
Weighted average yield - After 10 years	6.51%	6.51%
Weighted Average Yield	6.51%	6.51%
Other
Amortized cost
Amortized cost - After 1 to 5 years	$ 500	$ 500
Amortized Cost	500	500
Gross unrecognized gains
Gross unrealized gains - After 1 to 5 years	0	0
Gross Unrealized Gains	0	0
Gross unrealized losses
Gross unrealized losses - After 1 to 5 years	0	0
Gross Unrealized Losses	0	0
Fair Value
Fair Value - After 1 to 5 years	500	500
Total investment securities held-to-maturity - Fair Value	$ 500	$ 500
Weighted Average Yield
Weighted average yield - After 1 to 5 years	2.97%	2.97%
Weighted Average Yield	2.97%	2.97%