Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Table Text Block]

The tables below present qualitative information for significant assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) as of September 30, 2021 and December 31, 2020:

		September 30, 2021
		Fair Value		Valuation Technique	Unobservable Input	Range		Weighted Average
(Dollars in thousands)		Fair Value		Valuation Technique	Unobservable Input	Minimum	Maximum	Weighted Average

Investment securities available-for-sale:

	Private label MBS	$	7,574	Discounted cash flows	Discount rate	12.7%	12.7%	12.7%
					Prepayment rate	4.8%	24.1%	15.8%
					Projected cumulative loss rate	0.2%	18.6%	9.6%

	Puerto Rico government obligations		2,894	Discounted cash flows	Discount rate	6.7%	6.7%	6.7%
					Projected cumulative loss rate	10.7%	10.7%	10.7%

		December 31, 2020
		Fair Value		Valuation Technique	Unobservable Input	Range		Weighted Average
(Dollars in thousands)		Fair Value		Valuation Technique	Unobservable Input	Minimum	Maximum	Weighted Average

Investment securities available-for-sale:

	Private label MBS	$	8,428	Discounted cash flows	Discount rate	12.2%	12.2%	12.2%
					Prepayment rate	1.2%	18.8%	12.1%
					Projected cumulative loss rate	2.6%	22.3%	10.2%

	Puerto Rico government obligations		2,899	Discounted cash flows	Discount rate	7.9%	7.9%	7.9%
					Projected cumulative loss rate	12.4%	12.4%	12.4%

Debt Securities, Held-to-maturity, Allowance for Credit Loss [Table Text Block]

The following table presents the activity in the ACL for debt securities held to maturity by major security type for the quarters and nine-month periods ended September 30, 2021 and 2020:

		Puerto Rico Municipal Bonds
		Quarter Ended		Quarter Ended
		September 30, 2021		September 30, 2020

(In thousands)
Beginning Balance		$	10,685	$	9,268
Initial allowance on purchases with credit deterioration
	("PCD") debt securities		-		1,269
Provision for credit losses - (benefit)			(2,368)		(361)
		$	8,317	$	10,176

		Puerto Rico Municipal Bonds
		Nine-Month Period Ended		Nine-Month Period Ended
		September 30, 2021		September 30, 2020

(In thousands)
Beginning Balance		$	8,845	$	-
Impact of adopting CECL			-		8,134
Initial allowance on purchases with credit deterioration
	("PCD") debt securities		-		1,269
Provision for credit losses - (benefit) expense			(528)		773
		$	8,317	$	10,176

Investments Classified by Contractual Maturity Date [Table Text Block]

The amortized cost, gross unrealized gains and losses recorded in other comprehensive (loss) income, ACL, estimated fair value, and weighted-average yield of investment securities available for sale by contractual maturities as of September 30, 2021 were as follows:

		September 30, 2021
		Amortized cost						ACL		Fair value
				Gross Unrealized								Weighted-
				gains		losses						average yield%
(Dollars in thousands)

U.S. Treasury securities:
	After 1 to 5 years	$	88,234	$	-	$	347	$	-	$	87,887	0.50

U.S. government-sponsored
	agencies' obligations:
	After 1 to 5 years		1,771,629		565		7,896		-		1,764,298	0.60
	After 5 to 10 years		494,941		268		7,825		-		487,384	0.86
	After 10 years		16,696		243		-		-		16,939	0.63

Puerto Rico government obligations:
	After 10 years (1)		3,680		-		478		308		2,894	-

United States and Puerto Rico
	government obligations		2,375,180		1,076		16,546		308		2,359,402	0.66

Mortgage-backed securities ("MBS"):
Freddie Mac (“FHLMC”) certificates:
	After 1 to 5 years		1,507		69		-		-		1,576	2.25
	After 5 to 10 years		133,601		3,023		232		-		136,392	1.57
	After 10 years		1,364,820		5,902		20,123		-		1,350,599	1.15
			1,499,928		8,994		20,355		-		1,488,567	1.18

Ginnie Mae (“GNMA”) certificates:
	Due within one year		3		-		-		-		3	1.79
	After 1 to 5 years		18,823		772		-		-		19,595	2.91
	After 5 to 10 years		30,149		158		119		-		30,188	0.49
	After 10 years		380,890		9,941		1,454		-		389,377	1.35
			429,865		10,871		1,573		-		439,163	1.36
Fannie Mae (“FNMA”) certificates:
	Due within one year		5,014		40		-		-		5,054	2.07
	After 1 to 5 years		21,646		559		-		-		22,205	2.85
	After 5 to 10 years		239,743		4,515		528		-		243,730	1.43
	After 10 years		1,547,907		13,111		17,854		-		1,543,164	1.22
			1,814,310		18,225		18,382		-		1,814,153	1.27
Collateralized mortgage obligations
	issued or guaranteed by the FHLMC,				`
	FNMA and GNMA:
	After 1 to 5 years		272		-		-		-		272	0.75
	After 5 to 10 years		40,202		114		494		-		39,822	1.09
	After 10 years		544,865		616		5,955		-		539,526	1.20
			585,339		730		6,449		-		579,620	1.19
Private label:
	After 10 years		10,709		-		2,286		849		7,574	2.12
Total MBS			4,340,151		38,820		49,045		849		4,329,077	1.24

Other
	Due within one year		500		-		-		-		500	0.72
	After 1 to 5 years		500		-		-		-		500	0.84
			1,000		-		-		-		1,000	0.78

Total investment securities
	available for sale	$	6,716,331	$	39,896	$	65,591	$	1,157	$	6,689,479	1.04


(1)	Consist of a residential pass-through MBS issued by the Puerto Rico Housing Finance Authority (“PRHFA”) that is collateralized by certain second mortgages originated under a program launched by the Puerto Rico government in 2010. During the second quarter of 2021, the Corporation placed this instrument in nonaccrual status based on the delinquency status of the underlying second mortgage loans collateral.

The amortized cost, gross unrealized gains and losses recorded in other comprehensive income (loss), ACL, estimated fair value, and weighted-average yield of investment securities available for sale by contractual maturities as of December 31, 2020 were as follows:

		December 31, 2020
		Amortized cost		Gross Unrealized				ACL		Fair value
				Gross Unrealized								Weighted-
				gains		losses						average yield%

(Dollars in thousands)

U.S. Treasury securities:
	Due within one year	$	7,498	$	9	$	-	$	-	$	7,507	1.65

U.S. government-sponsored
	agencies' obligations:
	Due within one year		24,413		273		-		-		24,686	1.95
	After 1 to 5 years		691,668		911		290		-		692,289	0.57
	After 5 to 10 years		441,454		821		347		-		441,928	0.83
	After 10 years		21,413		-		149		-		21,264	0.65

Puerto Rico government obligations:
	After 10 years (1)		3,987		-		780		308		2,899	6.97
United States and Puerto Rico
	government obligations		1,190,433		2,014		1,566		308		1,190,573	0.72

MBS:
FHLMC certificates:
	After 1 to 5 years		75		8		-		-		83	4.86
	After 5 to 10 years		60,773		2,850		-		-		63,623	2.15
	After 10 years		1,070,984		15,340		159		-		1,086,165	1.38
			1,131,832		18,198		159		-		1,149,871	1.42
GNMA certificates:
	Due within one year		1		-		-		-		1	1.93
	After 1 to 5 years		26,918		1,080		-		-		27,998	2.91
	After 5 to 10 years		40,727		128		69		-		40,786	0.42
	After 10 years		614,584		16,271		148		-		630,707	1.27
			682,230		17,479		217		-		699,492	1.29
FNMA certificates:
	After 1 to 5 years		24,812		891		-		-		25,703	2.81
	After 5 to 10 years		110,832		5,783		-		-		116,615	2.13
	After 10 years		1,154,707		23,459		203		-		1,177,963	1.53
			1,290,351		30,133		203		-		1,320,281	1.61
Collateralized mortgage obligations issued or
	guaranteed by the FHLMC, FNMA
	and GNMA:
	After 1 to 5 years		538		-		1		-		537	0.81
	After 5 to 10 years		18,438		152		-		-		18,590	0.80
	After 10 years		258,069		1,019		491		-		258,597	1.56
			277,045		1,171		492		-		277,724	1.51
Private label:
	After 10 years		12,310		-		2,880		1,002		8,428	2.25
Total MBS			3,393,768		66,981		3,951		1,002		3,455,796	1.47

Other
	After 1 to 5 years		650		-		-		-		650	2.94
Total investment securities
	available for sale	$	4,584,851	$	68,995	$	5,517	$	1,310	$	4,647,019	1.28


(1)	Consist of a residential pass-through MBS issued by the PRHFA that is collateralized by certain second mortgages originated under a program launched by the Puerto Rico government in 2010.

Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Table Text Block]

The Corporation determined the ACL for private label MBS based on a risk-adjusted discounted cash flow methodology that considers the structure and terms of the instruments. The Corporation utilized probability of default (“PDs”) and loss given default (“LGDs”) that considered, among other things, historical payment performance, loan-to-value attributes and relevant current and forward-looking macroeconomic variables, such as regional unemployment rates and the housing price index. Under this approach, all future cash flows (interest and principal) from the underlying collateral loans, adjusted by prepayments and the PDs and LGDs, were discounted at the effective interest rate as of the reporting date. Significant assumptions in the valuation of the private label MBS were as follows:

	As of			As of
	September 30, 2021			December 31, 2020
	Weighted	Range		Weighted	Range
	Average	Minimum	Maximum	Average	Minimum	Maximum

Discount rate	12.7%	12.7%	12.7%	12.2%	12.2%	12.2%
Prepayment rate	15.8%	4.8%	24.1%	12.1%	1.2%	18.8%
Projected Cumulative Loss Rate	9.6%	0.2%	18.6%	10.2%	2.6%	22.3%

Other Than Temporary Impairment Credit Losses Recognized In Earnings [Line Items]

Schedule Of Unrealized Loss On Investments [Table Text Block]

The following tables show the Corporation’s held-to-maturity investments’ fair value and gross unrecognized losses, aggregated by investment category and length of time that individual securities had been in a continuous unrecognized loss position, as of September 30, 2021 and December 31, 2020, including debt securities for which an ACL was recorded:

	As of September 30, 2021
	Less than 12 months				12 months or more				Total
			Unrecognized				Unrecognized				Unrecognized
	Fair Value		Losses		Fair Value		Losses		Fair Value		Losses
(In thousands)
Debt securities:
Puerto Rico municipal bonds	$	-	$	-	$	117,787	$	9,929	$	117,787	$	9,929


	As of December 31, 2020
	Less than 12 months				12 months or more				Total
			Unrecognized				Unrecognized				Unrecognized
	Fair Value		Losses		Fair Value		Losses		Fair Value		Losses
(In thousands)
Debt securities:
Puerto Rico municipal bonds	$	28,252	$	1,611	$	116,216	$	16,027	$	144,468	$	17,638