GOODWILL AND OTHER INTANGIBLE ASSETS (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 Years	Dec. 31, 2010 Years
Finite-lived intangible assets
Cost	$ 212,188	$ 175,033
Accumulated Amortization	72,544	60,633
Net	139,644	114,400
Weighted Average Amortization Period (in years)	10.0	9.7
Permits
Finite-lived intangible assets
Cost	106,939	103,493
Accumulated Amortization	45,629	42,430
Net	61,310	61,063
Weighted Average Amortization Period (in years)	17.9	15.9
Customer relationships
Finite-lived intangible assets
Cost	83,721	58,322
Accumulated Amortization	17,650	10,418
Net	66,071	47,904
Weighted Average Amortization Period (in years)	7.9	8.0
Other intangible assets
Finite-lived intangible assets
Cost	21,528	13,218
Accumulated Amortization	9,265	7,785
Net	$ 12,263	$ 5,433
Weighted Average Amortization Period (in years)	5.3	3.5