GOODWILL AND INTANGIBLE ASSETS - Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Change in carrying amount of goodwill
Balance at the beginning of the period	$ 75,953	$ 73,450	$ 64,900
Acquired goodwill	2,503	8,550
Balance at the end of the period	75,953	$ 73,450
Goodwill impairment loss	$ 0