NATURE OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Nature of business (Detail)	Dec. 31, 2018 subsidiaries offices numberofbranches
FirstBank [Member] | PUERTO RICO [Member]
Nature Of Business [Line Items]
Wholly owned subsidiaries | subsidiaries	6
Banking branches	46
FirstBank [Member] | U S [Member]
Nature Of Business [Line Items]
Banking branches	10
FirstBank [Member] | USVI and BVI [Member]
Nature Of Business [Line Items]
Banking branches	11
First Federal Finance Corp [Member] | PUERTO RICO [Member]
Nature Of Business [Line Items]
Offices | offices	28