Debt Securities Held-to-maturity - Weighted average yield and contractual maturities of debt securities HTM (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Amortized cost
Amortized cost	$ 89,725	$ 92,621
Allowance for credit losses
Less - Allowance for credit losses	10,096	10,261
Net of Allowance
Net of Allowance	79,629	82,360
Gross unrecognized gains
Gross Unrealized Gains	13,014	12,554
Gross unrealized losses
Gross Unrealized Losses	0	23
Fair Value
Fair value	$ 92,643	$ 94,891
Weighted Average Yield
Weighted Average Yield	3.29%	3.38%
Obligations of Puerto Rico, States and political subdivisions
Amortized cost
Amortized cost - Within 1 year	$ 4,165	$ 3,990
Amortized cost - After 1 to 5 years	14,765	16,030
Amortized cost - After 5 to 10 years	13,210	14,845
Amortized cost - After 10 years	45,993	46,164
Amortized cost	78,133	81,029
Allowance for credit losses
Allowance for credit losses - Within 1 Year	69	50
Allowance for credit losses - After 1 to 5 years	619	710
Allowance for credit losses - After 5 to 10 years	440	573
Allowance for credit losses - After 10 years	8,968	8,928
Less - Allowance for credit losses	10,096	10,261	$ 13,390	$ 0
Net of Allowance
Net of Allowance - Within 1 Year	4,096	3,940
Net of Allowance - After 1 to 5 Years	14,146	15,320
Net of Allowance - After 5 to 10 Years	12,770	14,272
Net of Allowance - After 10 Years	37,025	37,236
Net of Allowance	68,037	70,768
Gross unrecognized gains
Gross unrealized gains - Within 1 year	69	47
Gross unrealized gains - After 1 to 5 years	619	710
Gross unrealized gains - After 5 to 10 years	235	295
Gross unrealized gains - After 10 years	12,090	11,501
Gross Unrealized Gains	13,013	12,553
Gross unrealized losses
Gross unrealized losses - Within 1 year	0	0
Gross unrealized losses - After 1 to 5 years	0	0
Gross unrealized losses - After 5 to 10 years	0	23
Gross unrealized losses - After 10 years	0	0
Gross Unrealized Losses	0	23
Fair Value
Fair Value - within 1 year	4,165	3,987
Fair Value - After 1 to 5 years	14,765	16,030
Fair Value - After 5 to 10 years	13,005	14,544
Fair Value - After 10 years	49,115	48,737
Fair value	$ 81,050	$ 83,298
Weighted Average Yield
Weighted average yield - Within 1 Year	6.07%	6.05%
Weighted average yield - After 1 to 5 years	6.20%	6.16%
Weighted average yield - After 5 to 10 years	2.33%	2.77%
Weighted average yield - After 10 years	1.57%	1.58%
Weighted Average Yield	2.81%	2.93%
Collateralized Mortgage Obligations - Federal agencies
Amortized cost
Amortized cost - After 1 to 5 years	$ 31	$ 31
Amortized cost	31	31
Allowance for credit losses
Allowance for credit losses - After 1 to 5 years	0	0
Less - Allowance for credit losses	0	0
Net of Allowance
Net of Allowance - After 1 to 5 Years	31	31
Net of Allowance	31	31
Gross unrecognized gains
Gross unrealized gains - After 1 to 5 years	1	1
Gross Unrealized Gains	1	1
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	32	32
Fair value	$ 32	$ 32
Weighted Average Yield
Weighted average yield - After 1 to 5 years	6.44%	6.44%
Weighted Average Yield	6.44%	6.44%
Securities in wholly owned statutory business trusts
Amortized cost
Amortized cost - After 10 years	$ 11,561	$ 11,561
Amortized cost	11,561	11,561
Allowance for credit losses
Allowance for credit losses - After 10 years	0	0
Less - Allowance for credit losses	0	0
Net of Allowance
Net of Allowance - After 10 Years	11,561	11,561
Net of Allowance	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
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%