EMPLOYEE BENEFIT PLAN - Net periodic benefit cost and related components (Details) (Multiple Employers Retirement Income Plan, USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Multiple Employers Retirement Income Plan
Multiemployer Plans [Line Item]
Service cost
Interest cost	487	436	973	870
Expected return on plan assets	(560)	(511)	(1,120)	(1,022)
Amortization of net losses	133	196	266	391
Net periodic benefit cost	$ 60	$ 121	$ 119	$ 239