Derivative Instruments (tables)

6 Months Ended

Jun. 30, 2013

Summary of Derivative Instruments [Abstract]

Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block]

	June 30,				December 31,
Dollars in thousands	2013		2012		2012
Open position absolute notional amount:
Natural gas (millions of therms)	35.9		35.1		39.5
Foreign exchange	$	17,171	$	13,725	$	13,231

Income Statement Presentation of Derivative Instruments [Text Block]

	Three Months Ended
	June 30, 2013						June 30, 2012
In thousands	Natural gas commodity			Foreign currency			Natural gas commodity			Foreign currency
Cost of sales increase (decrease)	$	(16,139	)	$	—		$	27,780		$	—
Other comprehensive loss	—			(274		)	—			(237		)
Less:
Amounts deferred to regulatory accounts	16,069			274			(27,780		)	237
Total loss in pre-tax earnings	$	(70	)	$	—		$	—		$	—

	Six Months Ended
	June 30, 2013						June 30, 2012
In thousands	Natural gas commodity			Foreign currency			Natural gas commodity			Foreign currency
Cost of sales increase (decrease)	$	(8,956	)	$	—		$	(28,114	)	$	—
Other comprehensive loss	—			(513		)	—			(111		)
Less:
Amounts deferred to regulatory accounts	9,032			513			28,114			111
Total gain in pre-tax earnings	$	76		$	—		$	—		$	—

Credit Rating Downgrade Scenarios [Text Block]

			Credit Rating Downgrade Scenarios
In thousands	(Current Ratings) A+/A3		BBB+/Baa1		BBB/Baa2		BBB-/Baa3		Speculative
With Adequate Assurance Calls	$	—	$	—	$	—	$	—	$	6,337
Without Adequate Assurance Calls	—		—		—		—		6,180