FIRST BANCORP. (Holding Company Only) Financial Information - Statements of Financial Condition (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Dec. 31, 2021
ASSETS
Cash and due from banks	$ 661,925	$ 478,480	$ 478,480	$ 2,540,376
Other assets	229,215	305,633
Total assets	18,909,549	18,634,484
Liabilities:
Long-term borrowings	161,700	183,762
Accounts payable and other liabilities	194,255	231,582
Liabilities	17,411,940	17,308,944
Stockholders Equity	1,497,609	1,325,540		$ 2,101,767
Total liabilities and stockholders' equity	18,909,549	18,634,484
Holding Company [Member]
ASSETS
Cash and due from banks	11,452	19,279
Other investment securities	825	735
Dividends receivable	713	624
Other assets	476	430
Total assets	1,670,436	1,519,376
Liabilities:
Long-term borrowings	161,700	183,762
Accounts payable and other liabilities	11,127	10,074
Liabilities	172,827	193,836
Stockholders Equity	1,497,609	1,325,540
Total liabilities and stockholders' equity	1,670,436	1,519,376
Holding Company [Member] | Investment In Banking Subsidiary [Member]
ASSETS
Investments	1,627,172	1,464,026
Holding Company [Member] | Non Banking Subsidiary [Member]
ASSETS
Investments	24,948	28,770
Holding Company [Member] | Statutory Trust One [Member]
ASSETS
Investments	1,289	1,951
Holding Company [Member] | Statutory Trust Two [Member]
ASSETS
Investments	$ 3,561	$ 3,561