INVESTMENT SECURITIES - Investment Securities Held to Maturity (Securities in continuous unrealized loss position) (Detail) - US States And Political Subdivisions Member [Member] - P R - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Schedule Of Held To Maturity Securities [Line Items]
Held to maturity less than twelve months fair value	$ 0	$ 4,163
Held to maturity less than twelve months unrealized losses	0	140
Held to maturity securities twelve months or longer fair value	132,241	127,381
Held to maturity securities twelve month or longer unrealized losses	23,949	29,799
Held to maturity unrealized loss position fair value	132,241	131,544
Held to maturity unrealized loss position aggregate losses	$ 23,949	$ 29,939