DERIVATIVE FINANCIAL INSTRUMENTS: Derivative Financial Instruments Level 4 (Details) (USD $)	Dec. 31, 2013		Dec. 31, 2012
Fair Value
Derivative Asset, Fair Value, Gross Asset	$ 2,248,000		$ 5,882,000
Derivative Asset, Fair Value, Gross Liability	(576,000)		(2,007,000)
Derivative Asset, Fair Value, Amount Offset Against Collateral	1,672,000		3,875,000
Derivative Liability, Fair Value, Gross Liability	2,204,000		2,356,000
Derivative Liability, Fair Value, Gross Asset	(1,632,000)		(1,301,000)
Derivative Liability, Fair Value, Amount Offset Against Collateral	572,000		1,055,000
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	1,100,000
Derivative Asset, Collateral, Obligation to Return Cash, Offset			700,000
Derivatives in a net liability position	2,100,000
Collateral Already Posted, Aggregate Fair Value	4,100,000
Additional Collateral, Aggregate Fair Value	10,000,000
Other current assets | Energy Related Derivative
Fair Value
Derivative Asset, Fair Value, Gross Asset	1,451,000		5,122,000
Derivative Asset, Fair Value, Gross Liability	(175,000)		(1,683,000)	[1]
Derivative Asset, Fair Value, Amount Offset Against Collateral	1,276,000		3,439,000
Derivative Liability, Fair Value, Gross Liability	175,000		978,000
Derivative Liability, Fair Value, Gross Asset	(175,000)		(978,000)
Derivative Liability, Fair Value, Amount Offset Against Collateral	0		0
Other current assets | Forward contracts
Fair Value
Derivative Asset, Fair Value, Gross Asset	109,000		155,000
Derivative Asset, Fair Value, Gross Liability	0		(4,000)
Derivative Asset, Fair Value, Amount Offset Against Collateral	109,000		151,000
Derivative Liability, Fair Value, Gross Liability			4,000
Derivative Liability, Fair Value, Gross Asset			(4,000)
Derivative Liability, Fair Value, Amount Offset Against Collateral			0
Other current liabilities | Energy Related Derivative
Fair Value
Derivative Asset, Fair Value, Gross Asset	373,000		320,000
Derivative Asset, Fair Value, Gross Liability	(373,000)		(320,000)
Derivative Asset, Fair Value, Amount Offset Against Collateral	0		0
Derivative Liability, Fair Value, Gross Liability	1,975,000		1,372,000
Derivative Liability, Fair Value, Gross Asset	(1,429,000)	[1]	(319,000)
Derivative Liability, Fair Value, Amount Offset Against Collateral	546,000		1,053,000
Other current liabilities | Forward contracts
Fair Value
Derivative Liability, Fair Value, Gross Liability	26,000		2,000
Derivative Liability, Fair Value, Gross Asset	0		0
Derivative Liability, Fair Value, Amount Offset Against Collateral	26,000		2,000
Other assets | Energy Related Derivative
Fair Value
Derivative Asset, Fair Value, Gross Asset	189,000		96,000
Derivative Asset, Fair Value, Gross Liability	(28,000)		0
Derivative Asset, Fair Value, Amount Offset Against Collateral	161,000		96,000
Derivative Liability, Fair Value, Gross Liability	28,000
Derivative Liability, Fair Value, Gross Asset	(28,000)
Derivative Liability, Fair Value, Amount Offset Against Collateral	0
Other assets | Forward contracts
Fair Value
Derivative Asset, Fair Value, Gross Asset	126,000		189,000
Derivative Asset, Fair Value, Gross Liability	0		0
Derivative Asset, Fair Value, Amount Offset Against Collateral	$ 126,000		$ 189,000
Electricity [Member] | Long [Member]
Fair Value
Derivative, Nonmonetary Notional Amount	89,000		405,000
Electricity [Member] | Short [Member]
Fair Value
Derivative, Nonmonetary Notional Amount	603,000		1,374,000
Fuel [Member] | Long [Member]
Fair Value
Derivative, Nonmonetary Notional Amount	10,804,000		13,477,000
Fuel [Member] | Short [Member]
Fair Value
Derivative, Nonmonetary Notional Amount	555,000		3,933,000
Diesel Fuel [Member] | Long [Member]
Fair Value
Derivative, Nonmonetary Notional Amount	906,000		834,000

[1] Current liability and current asset derivative amounts offset include $1.1 million and $0.7 million of collateral receivable and payable for the periods ending December 31, 2013 and 2012, respectively.