OTHER EQUITY SECURITIES - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Schedule Of Other Assets [Line Items]
Capital stock par value	$ 100		$ 100
Book value of investment in FHLB stock	$ 49.9		$ 49.9		$ 40.8
Dividend income from FHLB stock	0.5	$ 0.4	1.5	$ 1.1
Carrying value of other equity security	$ 2.2		$ 2.2		$ 2.2