FIRST BANCORP. (Holding Company Only) Financial Information - Statements of Financial Condition (Detail) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023
ASSETS
Cash and due from banks	$ 680,734	$ 661,925	$ 822,542
Other assets	258,457	229,215
Total assets	18,890,961	18,909,549
Liabilities:
Long-term borrowings	161,700	161,700
Accounts payable and other liabilities	204,033	194,255
Liabilities	17,411,244	17,411,940
Stockholders Equity	1,479,717	1,497,609	$ 1,405,593
Total liabilities and stockholders' equity	18,890,961	18,909,549
Holding Company [Member]
ASSETS
Cash and due from banks	11,420	11,452
Other investment securities	975	825
Dividends receivable	709	713
Other assets	679	476
Total assets	1,648,172	1,663,864
Liabilities:
Long-term borrowings	161,700	161,700
Accounts payable and other liabilities	6,755	4,555
Liabilities	168,455	166,255
Stockholders Equity	1,479,717	1,497,609
Total liabilities and stockholders' equity	1,648,172	1,663,864
Holding Company [Member] | Investment In Banking Subsidiary [Member]
ASSETS
Investments	1,608,030	1,627,172
Holding Company [Member] | Non Banking Subsidiary [Member]
ASSETS
Investments	21,509	18,376
Holding Company [Member] | Statutory Trust One [Member]
ASSETS
Investments	1,289	1,289
Holding Company [Member] | Statutory Trust Two [Member]
ASSETS
Investments	$ 3,561	$ 3,561