INVESTMENT SECURITIES - Additional Information (Detail) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($) position	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) position	Sep. 30, 2016 USD ($)
Investment [Line Items]
Percentage of debt securities considered to be of investment-grade	98.00%		98.00%
Maximum percentage of any general obligation bonds in one state			9.00%
Percent of tax exempt securities insured	2.00%		2.00%
Securities in unrealized loss positions, number of positions	680		680
Number of positions	2,320		2,320
Other-than-temporary impairments | $	$ 0.0	$ 0.0	$ 0.0	$ 0.0