BUSINESS COMBINATIONS (Other 2012 Acquisitions) (Details) (Other 2012 Acquisitions [Member], USD $)	3 Months Ended			12 Months Ended
	Mar. 31, 2013		Mar. 31, 2012	Dec. 31, 2012
Business Acquisition [Line Items]
Acquisition-related costs	$ 200,000
Combined purchase price				107,700,000
Assumption of long-term debt				7,700,000
Post-closing adjustment to purchase price				(900,000)
Purchase Price Allocation
Current assets				20,594,000	[1]
Property, plant and equipment				51,893,000
Customer relationships and other intangibles				21,770,000
Other assets				57,000
Current liabilities				(5,456,000)
Deferred taxes, unrecognized tax benefits and other long-term liabilities				(5,206,000)
Total identifiable net assets				83,652,000
Goodwill				24,085,000	[2]
Total				107,737,000
Other current assets, Measurement Period Adjustment	324,000	[1]
Property, plant and equipment, Measurement Period Adjustment	(8,000)
Permits and other intangibles, Measurement Period Adjustment	0
Other assets, Measurement Period Adjustment	4,000
Current liabilities, Measurement Period Adjustment	(179,000)
Other liabilities, Measurement Period Adjustments	(73,000)
Total identiiable net assets, Measurement Period Adjustments	68,000
Goodwill, Measurement Period Adjustments	129,000	[2]
Total, Measurement Period Adjustments	197,000
Preliminary fair value of customer receivables				13,000,000
Gross amounts of customer receivables				13,500,000
Business Acquisition, Pro Forma Information [Abstract]
Pro forma combined revenues			607,482,000
Pro forma combined net income			36,098,000
Scenario, Previously Reported [Member]
Purchase Price Allocation
Current assets				20,270,000	[1]
Property, plant and equipment				51,901,000
Customer relationships and other intangibles				21,770,000
Other assets				53,000
Current liabilities				(5,277,000)
Deferred taxes, unrecognized tax benefits and other long-term liabilities				(5,133,000)
Total identifiable net assets				83,584,000
Goodwill				23,956,000	[2]
Total				$ 107,540,000

[1] The preliminary fair value of the financial assets acquired included customer receivables with an aggregate fair value of $13.0 million. Combined gross amounts due were $13.5 million.

[2] Goodwill represents the excess of the fair value of the net assets acquired over the purchase price attributed to expected operating and cross selling synergies. The goodwill has been assigned to the Industrial and Field Services segment and will not be deductible for tax purposes.