FIRST BANCORP. (Holding Company Only) Financial Information - Statements of Income (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income:
Interest income on money market investments	$ 13,808	$ 13,985	$ 44,222	$ 44,723
Other income	405	4,081	2,950	10,311
Total interest income	170,402	172,295	494,282	508,277
Expense:
Gains Losses On Extinguishment Of Debt	94	0	94	0
Income tax (benefit) expense	4,405	(19,268)	1,326	(54,897)
Net income	28,613	46,327	52,135	130,928
Other comprehensive income, net of tax	(7,943)	7,562	38,563	45,539
Comprehensive income	20,670	53,889	90,698	176,467
Holding Company [Member]
Income:
Interest income on money market investments	12	44	60	189
Other income	51	70	399	216
Total interest income	14,545	7,864	41,829	28,905
Expense:
Other borrowings	1,356	2,331	5,029	7,210
Other operating expenses	607	644	1,665	1,749
Total operating expenses	1,963	2,975	6,694	8,959
Gains Losses On Extinguishment Of Debt	94	0	94	0
Income before income taxes and equity in undistributed earnings of subsidiaries	12,676	4,889	35,229	19,946
Income tax (benefit) expense	448	1,037	1,671	2,376
Equity in undistributed earnings of subsidiaries	16,385	42,475	18,577	113,358
Net income	28,613	46,327	52,135	130,928
Other comprehensive income, net of tax	(7,943)	7,562	38,563	45,539
Comprehensive income	20,670	53,889	90,698	176,467
Investment In Banking Subsidiary [Member] | Holding Company [Member]
Income:
Dividend income	$ 14,482	$ 7,750	$ 41,370	$ 28,500