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
	Mar. 31, 2014	Mar. 31, 2013
Multiple Employers Retirement Income Plan
Multiemployer Plans [Line Item]
Interest cost	$ 486	$ 435
Expected return on plan assets	(560)	(510)
Amortization of net losses	133	196
Net periodic benefit cost	$ 59	$ 121