INVESTMENT SECURITIES - Investment Securities Held to Maturity (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Schedule Of Held To Maturity Securities [Line Items]
Held to Maturity Fair value	$ 173,806	$ 110,374
Allowance for credit losses, Held-to-Maturity securities	8,845	0
Municipal Bonds [Member] | Puerto Rico [Member]
Schedule Of Held To Maturity Securities [Line Items]
Held to Matury Amortized Due Withing One Year	556	321
Held to Maturity Gross Unrecognized gain Due Within One Year	7	0
Held to Maturity Gross Unrecognized losses Due Within One Year	0	6
Held to Maturity Fair value Due Within One Year	563	$ 315
Allowance for credit losses Due within one year	$ 0
Held to Maturity Weighted-average yield Due withing One Year	5.41%	5.84%
Held to Maturity Amortized Cost After 1 to 5 years	$ 17,297	$ 8,264
Held to Maturity Gross Unrecognized gains After 1 to 5 years	561	0
Held to Maturity Gross Unrecognized losses After 1 to 5 years	305	736
Held to Maturity Fair value After 1 to 5 years	17,553	$ 7,528
Allowance for credit losses After 1 to 5 years	$ 576
Held to Maturity Weighted-average yield After 1 to 5 years	3.00%	5.18%
Held to Maturity Amortized Cost After 5 to 10 years	$ 88,394	$ 56,511
Held to Maturity Gross Unrecognized gains After 5 to 10 yearss	1,388	0
Held to Maturity Gross Unrecognized losses After 5 to 10 years	3,146	8,646
Held to Maturity Fair value After 5 to 10 years	86,636	$ 47,865
Allowance for credit losses After 5 to 10 years	$ 4,401
Held to Maturity Weighted-average yield After 5 to 10 years	4.66%	5.77%
Held to Maturity Amortized Cost After 10 years	$ 83,241	$ 73,579
Held to Maturity Gross Unrecognized gains After 10 years	0	0
Held to Maturity Gross Unrecognized losses After 10 years	14,187	18,913
Held to Maturity Fair value After 10 years	69,054	$ 54,666
Allowance for credit losses After 10 years	$ 3,868
Held to Maturity Weighted-average yield After 10 years	3.57%	5.44%
Held To Maturity Securities Amortized	$ 189,488	$ 138,675
Held to Maturity Gross Unrecognized gains	1,956	0
Held to Maturity Gross Unrecognized losses	17,638	28,301
Held to Maturity Fair value	173,806	110,374
Allowance for credit losses, Held-to-Maturity securities	$ 8,845	$ 0
Held to Maturity Weighted-average yield	4.03%	5.56%