INVESTMENT SECURITIES - Investment Securities Held to Maturity (Securities in continous unrealized loss position) (Detail) - Nontaxable Municipal Bonds [Member] - Puerto Rico [Member] - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Schedule Of Held To Maturity Securities [Line Items]
Fair value less than 12 months	$ 0	$ 4,163
Unrealized losses less than 12 months	0	140
Fair value 12 months or more	132,759	127,381
Unrealized losses 12 months or more	23,431	29,799
Total fair value	132,759	131,544
Total unrealized losses	$ 23,431	$ 29,939