GOODWILL AND OTHER INTANGIBLE ASSETS--Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 204,100		$ 204,084
Intangible Assets, Net (Excluding Goodwill)	5,000		5,300
Finite-Lived Core Deposits, Gross	3,100		$ 3,300
Finite-Lived Intangible Assets, Amortization Expense	$ 300	$ 300
Core Deposits [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets amortization method	accelerated basis
Estimated weighted average life (in years)	3 years 7 months 6 days