GOODWILL AND INTANGIBLE ASSETS - Acquired Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Acquired intangible assets
Accumulated amortization	$ (28,910)	$ (27,568)
Purchased intangibles, net	7,419	4,662
Aggregate amortization expense	1,342	1,640	$ 1,690
Estimated amortization expense
2017	1,244
2018	1,170
2019	991
2020	896
2021	789
Core deposit intangibles
Acquired intangible assets
Purchased intangibles, gross	34,135	30,036
Other customer relationship intangibles
Acquired intangible assets
Purchased intangibles, gross	$ 2,194	$ 2,194