GOODWILL AND INTANGIBLE ASSETS - Acquired Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Acquired intangible assets
Accumulated amortization	$ (27,568)	$ (25,928)
Purchased intangibles, net	4,662	5,096
Aggregate amortization expense	1,640	1,690	$ 1,868
Estimated amortization expense
2016	1,048
2017	676
2017	601
2018	489
2019	468
Core deposit
Acquired intangible assets
Purchased intangibles, gross	30,036	28,830
Other customer relationship intangibles
Acquired intangible assets
Purchased intangibles, gross	$ 2,194	$ 2,194