Debt Securities Held-to-maturity - Credit quality indicators (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Debt securities held to maturity credit quality indicator
Debt securities held-to-maturity	$ 95,263	$ 97,662
Obligations of Puerto Rico, States and political subdivisions
Debt securities held to maturity credit quality indicator
Debt securities held-to-maturity	83,161	85,556
Obligations of Puerto Rico, States and political subdivisions | Munis Payable From Real and Personal Property Taxes
Debt securities held to maturity credit quality indicator
Debt securities held-to-maturity	37,625
Collateralized Mortgage Obligations - Federal agencies
Debt securities held to maturity credit quality indicator
Debt securities held-to-maturity	41	45
Securities in wholly owned statutory business trusts
Debt securities held to maturity credit quality indicator
Debt securities held-to-maturity	11,561	11,561
Other
Debt securities held to maturity credit quality indicator
Debt securities held-to-maturity	500	$ 500
Watch | Obligations of Puerto Rico, States and political subdivisions | Munis Payable From Real and Personal Property Taxes
Debt securities held to maturity credit quality indicator
Debt securities held-to-maturity	22,230
Special Mention | Obligations of Puerto Rico, States and political subdivisions | Munis Payable From Real and Personal Property Taxes
Debt securities held to maturity credit quality indicator
Debt securities held-to-maturity	$ 15,395