INVESTMENT SECURITIES - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($) position	Mar. 31, 2017 USD ($)
Investments, Debt and Equity Securities [Abstract]
Percentage of debt securities considered to be of investment-grade	99.00%
Maximum percentage of any general obligation bonds in one state	9.00%
Percent of tax exempt securities insured	2.00%
Securities in unrealized loss positions, number of positions	1,410
Number of positions	2,230
Other-than-temporary impairments | $	$ 0.0	$ 0.0