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, 2018		Dec. 31, 2017
Schedule of Held-to-maturity Securities [Line Items]
Debt securities held-to-maturity, fair value	$ 98,740	[1]	$ 97,501	[2]
Gross Unrealized Gains	3,316		3,838
Gross Unrealized Losses	9,393		13,356
Amortized Cost	$ 104,817	[1]	$ 107,019	[2]
Weighted Average Yield	3.73%		3.79%
Obligations of Puerto Rico, States and political subdivisions
Schedule of Held-to-maturity Securities [Line Items]
Debt securities held-to-maturity, fair value	$ 84,726		$ 83,239
Gross Unrealized Gains	3,312		3,834
Gross Unrealized Losses	9,389		13,349
Amortized Cost	$ 90,803		$ 92,754
Weighted Average Yield	3.30%		3.38%
Obligations of Puerto Rico, States and political subdivisions | Within 1 year
Schedule of Held-to-maturity Securities [Line Items]
Debt securities held-to-maturity, fair value	$ 3,174		$ 3,216
Gross Unrealized Gains	0		0
Gross Unrealized Losses	271		79
Amortized Cost	$ 3,445		$ 3,295
Weighted Average Yield	5.98%		5.96%
Obligations of Puerto Rico, States and political subdivisions | After 1 and within 5 years
Schedule of Held-to-maturity Securities [Line Items]
Debt securities held-to-maturity, fair value	$ 12,914		$ 11,342
Gross Unrealized Gains	0		0
Gross Unrealized Losses	3,281		4,143
Amortized Cost	$ 16,195		$ 15,485
Weighted Average Yield	6.06%		6.05%
Obligations of Puerto Rico, States and political subdivisions | After 5 to 10 years
Schedule of Held-to-maturity Securities [Line Items]
Debt securities held-to-maturity, fair value	$ 20,552		$ 20,335
Gross Unrealized Gains	0		0
Gross Unrealized Losses	5,588		8,905
Amortized Cost	$ 26,140		$ 29,240
Weighted Average Yield	3.62%		3.89%
Obligations of Puerto Rico, States and political subdivisions | After 10 years
Schedule of Held-to-maturity Securities [Line Items]
Debt securities held-to-maturity, fair value	$ 48,086		$ 48,346
Gross Unrealized Gains	3,312		3,834
Gross Unrealized Losses	249		222
Amortized Cost	$ 45,023		$ 44,734
Weighted Average Yield	1.91%		1.93%
Collateralized Mortgage Obligations - Federal agencies
Schedule of Held-to-maturity Securities [Line Items]
Debt securities held-to-maturity, fair value	$ 70		$ 71
Gross Unrealized Gains	4		4
Gross Unrealized Losses	0		0
Amortized Cost	$ 66		$ 67
Weighted Average Yield	5.45%		5.45%
Collateralized Mortgage Obligations - Federal agencies | After 5 to 10 years
Schedule of Held-to-maturity Securities [Line Items]
Debt securities held-to-maturity, fair value	$ 70		$ 71
Gross Unrealized Gains	4		4
Gross Unrealized Losses	0		0
Amortized Cost	$ 66		$ 67
Weighted Average Yield	5.45%		5.45%
Trust preferred securities
Schedule of Held-to-maturity Securities [Line Items]
Debt securities held-to-maturity, fair value	$ 13,198		$ 13,198
Gross Unrealized Gains	0		0
Gross Unrealized Losses	0		0
Amortized Cost	$ 13,198		$ 13,198
Weighted Average Yield	6.73%		6.73%
Trust preferred securities | After 5 to 10 years
Schedule of Held-to-maturity Securities [Line Items]
Debt securities held-to-maturity, fair value	$ 1,637		$ 1,637
Gross Unrealized Gains	0		0
Gross Unrealized Losses	0		0
Amortized Cost	$ 1,637		$ 1,637
Weighted Average Yield	8.33%		8.33%
Trust preferred securities | After 10 years
Schedule of Held-to-maturity Securities [Line Items]
Debt securities held-to-maturity, fair value	$ 11,561		$ 11,561
Gross Unrealized Gains	0		0
Gross Unrealized Losses	0		0
Amortized Cost	$ 11,561		$ 11,561
Weighted Average Yield	6.51%		6.51%
Other
Schedule of Held-to-maturity Securities [Line Items]
Debt securities held-to-maturity, fair value	$ 746		$ 993
Gross Unrealized Gains	0		0
Gross Unrealized Losses	4		7
Amortized Cost	$ 750		$ 1,000
Weighted Average Yield	2.79%		2.47%
Other | Within 1 year
Schedule of Held-to-maturity Securities [Line Items]
Debt securities held-to-maturity, fair value	$ 250		$ 493
Gross Unrealized Gains	0		0
Gross Unrealized Losses	0		7
Amortized Cost	$ 250		$ 500
Weighted Average Yield	2.44%		1.96%
Other | After 1 and within 5 years
Schedule of Held-to-maturity Securities [Line Items]
Debt securities held-to-maturity, fair value	$ 496		$ 500
Gross Unrealized Gains	0		0
Gross Unrealized Losses	4		0
Amortized Cost	$ 500		$ 500
Weighted Average Yield	2.97%		2.97%

[1] Includes $90.8 million pledged to secure public and trust deposits that the secured parties are not permitted to sell or repledge the collateral.

[2] Includes $92.8 million pledged to secure public and trust deposits that the secured parties are not permitted to sell or repledge the collateral.