Derivative Instruments (Tables)

6 Months Ended

Jun. 30, 2016

Derivative Instruments and Hedging Activities Disclosure [Abstract]

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

	June 30,				December 31,
In thousands	2016		2015		2015
Natural gas (in therms):
Financial	517,980		350,250		346,875
Physical	398,980		296,250		404,645
Foreign exchange	$	7,254	$	7,920	$	9,025

Income Statement Presentation of Derivative Instruments [Text Block]

	Three Months Ended June 30,
	2016						2015
In thousands	Natural gas commodity			Foreign exchange			Natural gas commodity			Foreign exchange
Benefit (expense) to cost of gas	$	23,237		$	(87	)	$	10,020		$	478
Operating revenues	29			—			(616		)	—
Less:
Amounts deferred to regulatory accounts on balance sheet	(23,271		)	87			(9,618		)	(478		)
Total (loss) gain in pre-tax earnings	$	(5	)	$	—		$	(214	)	$	—

	Six Months Ended June 30,
	2016						2015
In thousands	Natural gas commodity			Foreign exchange			Natural gas commodity			Foreign exchange
Benefit (expense) to cost of gas	$	6,858		$	154		$	(13,461	)	$	(263	)
Operating revenues	29			—			22			—
Less:
Amounts deferred to regulatory accounts on balance sheet	(6,892		)	(154		)	13,447			263
Total (loss) gain in pre-tax earnings	$	(5	)	$	—		$	8		$	—

Table Of Estimated Collateral Calls Table [Text Block]

			Credit Rating Downgrade Scenarios
In thousands	(Current Ratings) A+/A3		BBB+/Baa1		BBB/Baa2		BBB-/Baa3		Speculative
With Adequate Assurance Calls	$	—	$	—	$	—	$	—	$	5,893
Without Adequate Assurance Calls	—		—		—		—		5,375