INTANGIBLE ASSETS (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Acquired Finite-Lived Intangible Assets
Intangible assets	$ 49,431,000		$ 49,431,000		$ 48,492,000
Accumulated amortization	20,801,000		20,801,000		18,397,000
Amortization expense	800,000	800,000	2,400,000	2,300,000
Expected amortization expense, year one	3,200,000		3,200,000
Expected amortization expense, year two	3,200,000		3,200,000
Expected amortization expense, year three	3,200,000		3,200,000
Expected amortization expense, year four	3,200,000		3,200,000
Expected amortization expense, year five	3,200,000		3,200,000
METC
Acquired Finite-Lived Intangible Assets
Intangible assets	38,000,000		38,000,000		40,300,000
Accumulated amortization	20,400,000		20,400,000		18,100,000
ITC Great Plains
Acquired Finite-Lived Intangible Assets
Intangible assets	11,400,000		11,400,000		8,200,000
Accumulated amortization	$ 400,000		$ 400,000		$ 300,000