UNION BARGAINING UNIT INTERMITTENT EMPLOYEES SEVERANCE PLAN (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Amounts recognized in the consolidated balance sheets consist of:
Accrued severance liability (non-current)	$ (713,000)	$ (587,000)
Amounts recognized in accumulated other comprehensive loss
Estimated net actuarial loss	0
Intermittent Severance Benefits
Union Bargaining Unit Intermittent Employees Severance Plan
Payment period for each year worked	8 days
Eligible service period for participating in the plan	3 years
Age to be reached by employees to be eligible for payment	60 years
Change in severance obligation:
Projected benefit obligation at beginning of year	367,000	377,000	326,000
Service cost	16,000	17,000	15,000
Interest cost	14,000	17,000	17,000
Actuarial loss	15,000	11,000	19,000
Benefits paid		(61,000)
Settlements		6,000
Projected benefit obligation at end of year	412,000	367,000	377,000
Change in plan assets:
Fair value of plan assets at beginning of year	0	0	0
Employer contributions		61,000
Benefits paid		(61,000)
Fair value of plan assets at end of year	0	0	0
Amounts recognized in the consolidated balance sheets consist of:
Accrued severance liability (current)	(61,000)	(57,000)	(55,000)
Accrued severance liability (non-current)	(351,000)	(310,000)	(322,000)
Net amount recognized	(412,000)	(367,000)	(377,000)
Amounts recognized in accumulated other comprehensive loss
Net actuarial loss	51,000	36,000	25,000
Components of net periodic pension cost
Service cost	16,000	17,000	15,000
Interest cost	14,000	17,000	17,000
Settlement loss		6,000
Net periodic pension cost	30,000	40,000	32,000
Amount recognized in accumulated other comprehensive loss during the period
Net actuarial loss recognized in other comprehensive income	15,000	11,000	19,000
Weighted average assumptions
Discount rate (as a percent)	3.70%	4.10%	4.96%
Rate of compensation increase (as a percent)	1.65%	1.65%	1.65%
Expected contribution to the plan in the next fiscal year	61,000
Benefit payments expected to be paid
2013	61,000
2014	26,000
2015	32,000
2016	48,000
2017	25,000
2018-2022	$ 144,000
Intermittent Severance Benefits | Minimum
Weighted average assumptions
Period for which yield curve of annualized individual discount rates was created in analysis	1 year
Intermittent Severance Benefits | Maximum
Weighted average assumptions
Period for which yield curve of annualized individual discount rates was created in analysis	30 years