EMPLOYEE BENEFIT PLAN - Net periodic benefit cost and related components (Details) - Multiple Employers Retirement Income Plan - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 474	$ 487	$ 1,422	$ 1,460
Expected return on plan assets	(565)	(560)	(1,695)	(1,680)
Amortization of net losses	198	133	594	399
Net periodic benefit cost	$ 107	$ 60	$ 321	$ 179