Debt Securities Held-to-maturity -Additional Information (Details)	Mar. 31, 2024 USD ($) score	Dec. 31, 2023 USD ($) score	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Schedule of Held-to-maturity Securities [Line Items]
Held to maturity securities	$ 8,697,641,000	$ 8,852,825,000
Allowance for credit losses	5,731,000	5,780,000
Obligations of Puerto Rico, States and political subdivisions
Schedule of Held-to-maturity Securities [Line Items]
Held to maturity securities	61,712,000	65,408,000
Allowance for credit losses	$ 5,731,000	$ 5,780,000	$ 6,792,000	$ 6,911,000
Average Credit Score Fico | score	708	708
Percentage of nominal value	68.00%	67.00%
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	$ 15,520,000	$ 18,820,000
Allowance for credit losses	200,000	200,000
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	39,000,000	40,000,000
Allowance for credit losses	5,600,000	5,600,000
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	7,000,000
Allowance for credit losses	0	0
Past due
Schedule of Held-to-maturity Securities [Line Items]
Held to maturity securities	$ 0	$ 0