LOAN PORTFOLIO - Activity for Impaired Loans (Parenthetical) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable Impaired [Line Items]
Transfer of Portfolio Loans and Leases to Held-for-sale	$ 90,319	$ 0	$ 10,332
Nonperforming Financial Instruments [Member]
Financing Receivable Impaired [Line Items]
Disposal Group, Not Discontinued Operation, Loss (Gain) on Write-down	22,200
Transfer of Portfolio Loans and Leases to Held-for-sale	74,400
Impaired Loans [Member] | Puerto Rico Electric Power Authority [Member]
Financing Receivable Impaired [Line Items]
Allowance For Loan And Lease Losses Write Offs Loans Sold		$ 10,700
Impaired Loans [Member] | Nonperforming Financial Instruments [Member]
Financing Receivable Impaired [Line Items]
Disposal Group, Not Discontinued Operation, Loss (Gain) on Write-down	22,200
Transfer of Portfolio Loans and Leases to Held-for-sale	$ 74,400
Allowance For Loan And Lease Losses Write Offs Loans Sold			4,200
Classified And Non Performing Loans Sold			$ 16,300