FIRST BANCORP. (Holding Company Only) Financial Information - Statements of Loss (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income:
Interest income on investment securities	$ 13,950,000	$ 13,552,000	$ 27,252,000	$ 28,171,000
Other Interest And Dividend Income	727,000	1,271,000	1,211,000	2,344,000
Expense:
Impairement on equity securities	371,000	0	371,000	8,000
Gains Losses On Extinguishment Of Debt	0	0	0	4,217,000
Segment income	62,896,000	52,779,000	105,766,000	106,957,000
Income tax expense	(9,290,000)	(7,523,000)	(1,217,000)	(13,246,000)
Net income	27,998,000	21,953,000	53,539,000	45,297,000
Other comprehensive income, net of tax	9,065,000	13,875,000	19,761,000	44,266,000
Comprehensive (loss) income	37,063,000	35,828,000	73,300,000	89,563,000
Holding Company [Member]
Income:
Other Interest And Dividend Income	5,000	5,000	10,000	10,000
Other income	66,000	63,000	128,000	123,000
Total interest income	1,871,000	31,226,000	3,738,000	38,291,000
Expense:
Notes payable and other borrowings	2,065,000	1,982,000	4,027,000	3,960,000
Other operating expenses	699,000	978,000	1,666,000	1,628,000
Total operating expenses	2,764,000	2,960,000	5,693,000	5,588,000
Gains Losses On Extinguishment Of Debt	0	0	0	4,217,000
Segment income	(893,000)	28,266,000	(1,955,000)	36,920,000
Equity in undistributed earnings (losses) of subsidiaries	28,891,000	(6,313,000)	55,494,000	8,377,000
Net income	27,998,000	21,953,000	53,539,000	45,297,000
Other comprehensive income, net of tax	9,065,000	13,875,000	19,761,000	44,266,000
Comprehensive (loss) income	37,063,000	35,828,000	73,300,000	89,563,000
Investment In Banking Subsidiary [Member] | Holding Company [Member]
Income:
Dividend Income From Subsidiaries	1,800,000	31,158,000	3,600,000	31,158,000
Non Banking Subsidiary [Member] | Holding Company [Member]
Income:
Dividend Income From Subsidiaries	$ 0	$ 0	$ 0	$ 7,000,000