FIRST BANCORP. (Holding Company Only) Financial Information - Statements of Financial Condition (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
ASSETS
Cash and due from banks	$ 1,433,261	$ 546,391	$ 578,613
Money market investments	60,572	97,708	7,590
Other assets	272,737	177,842
Total assets	18,793,071	12,611,266
Liabilities:
Other borrowings	183,762	184,150
Accounts payable and other liabilities	276,747	180,614
Liabilities	16,517,892	10,383,193
Stockholders Equity	2,275,179	2,228,073	2,044,704
Total liabilities and stockholders' equity	18,793,071	12,611,266
Holding Company [Member]
ASSETS
Cash and due from banks	10,909	16,895
Money market investments	6,211	6,211	$ 6,111
Other investment securities	285	285
Other assets	2,023	509
Total assets	2,463,216	2,416,601
Liabilities:
Other borrowings	183,762	184,150
Accounts payable and other liabilities	4,275	4,378
Liabilities	188,037	188,528
Stockholders Equity	2,275,179	2,228,073
Total liabilities and stockholders' equity	2,463,216	2,416,601
Holding Company [Member] | Firstbank Puerto Rico [Member]
ASSETS
Equity Method Investments	2,396,963	2,362,182
Holding Company [Member] | FirstBank Insurance Agency
ASSETS
Equity Method Investments	41,313	24,995
Holding Company [Member] | FBP Statutory Trust I [Member]
ASSETS
Equity Method Investments	1,951	1,963
Holding Company [Member] | FBP Statutory Trust II [Member]
ASSETS
Equity Method Investments	$ 3,561	$ 3,561