INTEREST AND DIVIDEND ON INVESTMENTS- Interest on investments and FHLB dividend income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other Income And Expenses [Line Items]
Mortgage-backed securities	$ 32,167	$ 37,299	$ 44,909
PR Government obligations, U.S. Treasury securities and U.S. Government agencies	17,276	16,476	14,294
Total Intesrest income investment securities	50,905	54,850	60,372
Interest on money market investments	3,365	2,148	1,892
Total interest and dividends on investments	54,270	56,998	62,264
Taxable [Member]
Other Income And Expenses [Line Items]
Mortgage-backed securities	11,246	13,520	16,303
PR Government obligations, U.S. Treasury securities and U.S. Government agencies	4,131	2,628	1,357
Other investment securities (including FHLB dividends)	1,462	1,075	1,169
Interest on money market investments	2,669	1,490	1,734
Exempt [Member]
Other Income And Expenses [Line Items]
Mortgage-backed securities	20,921	23,779	28,606
PR Government obligations, U.S. Treasury securities and U.S. Government agencies	13,145	13,848	12,937
Interest on money market investments	$ 696	$ 658	$ 158