EMPLOYEE BENEFIT PLAN - Net periodic benefit cost and related components (Details) - Multiple Employers Retirement Income Plan - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 474	$ 487	$ 948	$ 973
Expected return on plan assets	(565)	(560)	(1,130)	(1,120)
Amortization of net losses	198	133	396	266
Net periodic benefit cost	$ 107	$ 60	$ 214	$ 119