EQUITY (Details) - USD ($)	1 Months Ended		12 Months Ended
	Jan. 31, 2017	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Nov. 30, 2017	Jan. 31, 2016	Jan. 31, 2015	May 20, 2014
EQUITY
Number of shares repurchased or acquired through tender offer			864,483	796,822	4,122,881
Central Bank
EQUITY
Retained earnings			$ 85,600,000
Common Stock | Repurchase Agreements
EQUITY
Number of shares repurchased					4,122,881
Amount authorized under the 2014 Repurchase Plan								$ 75,000,000	$ 30,000,000
Repurchased amount					$ 93,500,000
Increase in authorized amount		$ 25,000,000
Common Stock | 2016 Repurchase Plan [Member]
EQUITY
Value of shares repurchased or acquired through tender offer	$ 100,000			$ 18,200,000
Number of shares repurchased or acquired through tender offer	1,750			796,822
Amount authorized under the 2014 Repurchase Plan	$ 30,000,000.0						$ 30,000,000.0
Common Stock | 2017 Repurchase Plan [Member]
EQUITY
Value of shares repurchased or acquired through tender offer			$ 26,600,000
Number of shares repurchased or acquired through tender offer			864,483
Amount authorized under the 2014 Repurchase Plan						$ 50,000,000.0
Remaining amount available for repurchase			$ 53,500,000