Loans Receivable (Narratives) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Accounts Notes And Loans Receivable Line Items
Financing Receivable Modifications Recorded Investment Not Included In Non Accrual	$ 97.7	$ 109.2
Originated Loans Granted To Puerto Rico Government	91.4	94.9
Acquired Credit Facilities Granted to the Puerto Rico Public Corporation	44.0	50.3
Impaired Commercial Loans	69.6	72.3
Allowance for impaired commercial loans	7.6	10.6
Impaired Mortgage Loans	85.1	85.4
Allowance For Impaired Mortgage Loans	10.6	9.1
Current but placed in non-accrual due to credit deterioration	$ 23.6	$ 20.1