FIRST BANCORP. (Holding Company Only) Financial Information - Statements of Financial Condition (Unaudited) (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
ASSETS
Cash and due from banks	$ 581,838	$ 578,613	$ 743,409
Money market investments	7,737	7,590	100,415
Other investment securities	44,438	44,530
Loans Receivable, net	8,846,259	8,704,947
Other assets	213,111	171,066
Total assets	12,376,780	12,243,561
Liabilities:
Other borrowings	184,150	184,150
Accounts payable and other liabilities	181,339	129,907
Total liabilities	10,276,323	10,198,857
Stockholders Equity	2,100,457	2,044,704	$ 1,877,104
Total liabilities and stockholders' equity	12,376,780	12,243,561
Holding Company [Member]
ASSETS
Cash and due from banks	22,536	10,984
Money market investments	6,111	6,111
Other investment securities	285	285
Other assets	3,615	12,219
Total assets	2,294,934	2,232,558
Liabilities:
Other borrowings	184,150	184,150
Accounts payable and other liabilities	10,327	3,704
Total liabilities	194,477	187,854
Stockholders Equity	2,100,457	2,044,704
Total liabilities and stockholders' equity	2,294,934	2,232,558
Holding Company [Member] | Investment in First Bank Puerto Rico, at equity [Member]
ASSETS
Equity Method Investments	2,235,568	2,179,655
Holding Company [Member] | Investment in First Bank Insurance Agency, at equity
ASSETS
Equity Method Investments	21,295	17,780
Holding Company [Member] | Statutory Trust One [Member]
ASSETS
Equity Method Investments	1,963	1,963
Holding Company [Member] | Statutory Trust Two [Member]
ASSETS
Equity Method Investments	$ 3,561	$ 3,561