FIRST BANCORP. (Holding Company Only) Financial Information - Statements of Income (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income:
Interest income on money market investments	$ 14,538	$ 14,720	$ 30,414	$ 30,738
Other income	283	3,401	2,545	6,230
Total interest income	158,616	169,510	323,880	335,982
Expense:
Income tax (benefit) expense	(6,046)	(18,011)	(3,079)	(35,629)
Net income	21,256	41,287	23,522	84,601
Other comprehensive income, net of tax	4,154	17,467	46,506	37,977
Comprehensive income	25,410	58,754	70,028	122,578
Holding Company [Member]
Income:
Interest income on money market investments	15	40	48	145
Other income	287	71	348	146
Total interest income	13,561	11,361	27,284	21,041
Expense:
Other borrowings	1,641	2,413	3,673	4,879
Other operating expenses	535	549	1,058	1,105
Total operating expenses	2,176	2,962	4,731	5,984
Income before income taxes and equity in undistributed earnings of subsidiaries	11,385	8,399	22,553	15,057
Income tax (benefit) expense	(159)	0	1,223	1,339
Equity in undistributed earnings of subsidiaries	9,712	32,888	2,192	70,883
Net income	21,256	41,287	23,522	84,601
Other comprehensive income, net of tax	4,154	17,467	46,506	37,977
Comprehensive income	25,410	58,754	70,028	122,578
Investment In Banking Subsidiary [Member] | Holding Company [Member]
Income:
Dividend income	$ 13,259	$ 11,250	$ 26,888	$ 20,750