FIRST BANCORP. (Holding Company Only) Financial Information - Statements of Income (Unaudited) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income:
Interest income on money market investments	$ 16,018	$ 13,987
Total interest income	166,472	149,418
Expense:
Gain on early extinguishment of debt	0	2,316
Income tax provision	(17,618)	(7,758)
Net income	43,314	33,148
Other comprehensive income (loss), net of tax	20,510	(24,053)
Comprehensive income	63,824	9,095
Holding Company [Member]
Income:
Interest income on money market investments	105	5
Other income	75	63
Total interest income	9,680	21,652
Expense:
Other borrowings	2,466	2,085
Other operating expenses	556	596
Total operating expenses	3,022	2,681
Gain on early extinguishment of debt	0	2,316
Income before income taxes and equity in undistributed earnings of subsidiaries	6,658	21,287
Income tax provision	1,339	0
Equity in undistributed earnings of subsidiaries	37,995	11,861
Net income	43,314	33,148
Other comprehensive income (loss), net of tax	20,510	(24,053)
Comprehensive income	63,824	9,095
Investment In Banking Subsidiary [Member] | Holding Company [Member]
Income:
Dividend income	$ 9,500	$ 21,584