Debt Securities Held-to-maturity -Additional Information (Details)	Sep. 30, 2023 USD ($) score	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($) score	Sep. 30, 2022 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)
Schedule of Held-to-maturity Securities [Line Items]
Held to maturity securities	$ 9,004,729,000		$ 9,356,739,000
Allowance for credit losses	6,057,000		6,911,000
Obligations of Puerto Rico, States and political subdivisions
Schedule of Held-to-maturity Securities [Line Items]
Held to maturity securities	65,802,000		65,921,000
Allowance for credit losses	$ 6,057,000	$ 6,145,000	$ 6,911,000	$ 7,210,000	$ 7,495,000	$ 8,096,000
Average Credit Score Fico | score	709		707
Percentage of nominal value	67.00%		65.00%
Obligations of Puerto Rico, States and political subdivisions | Munis Payable From Real and Personal Property Taxes
Schedule of Held-to-maturity Securities [Line Items]
Held to maturity securities	$ 18,820,000		$ 24,660,000
Allowance for credit losses	200,000		300,000
Obligations of Puerto Rico, States and political subdivisions | Munis Not Guaranteed By Puerto Rico Central Government
Schedule of Held-to-maturity Securities [Line Items]
Held to maturity securities	40,000,000		42,000,000
Allowance for credit losses	5,900,000		6,600,000
Obligations of Puerto Rico, States and political subdivisions | Munis payable from US treasure securities proceeds
Schedule of Held-to-maturity Securities [Line Items]
Held to maturity securities	7,000,000
Allowance for credit losses	0
Past due
Schedule of Held-to-maturity Securities [Line Items]
Held to maturity securities	$ 0		$ 0