Derivative Instruments (Tables)

9 Months Ended

Sep. 30, 2015

Derivative Instruments, Gain (Loss) [Line Items]

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	$	—	$	—	$	—	$	—	$	22,066
Without Adequate Assurance Calls	—		—		—		—		15,937

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

	September 30,				December 31,
In thousands	2015		2014		2014
Natural gas (in therms):
Financial	416,075		368,425		287,475
Physical	521,350		620,550		420,980
Foreign exchange	$	8,023	$	10,296	$	12,230

Income Statement Presentation of Derivative Instruments [Text Block]

	Nine Months Ended September 30,
	2015						2014
In thousands	Natural gas commodity			Foreign currency			Natural gas commodity			Foreign currency
(Expense) benefit to cost of gas	$	(21,876	)	$	(413	)	$	360		$	(242	)
Operating revenues	55			—			—			—
Less:
Amounts deferred to regulatory accounts on the balance sheet	21,838			413			(93		)	242
Total gain in pre-tax earnings	$	17		$	—		$	267		$	—

	Three Months Ended September 30,
	2015						2014
In thousands	Natural gas commodity			Foreign currency			Natural gas commodity			Foreign currency
Expense to cost of gas	$	(8,415	)	$	(150	)	$	(10,173	)	$	(421	)
Operating revenues	33			—			—			—
Less:
Amounts deferred to regulatory accounts on the balance sheet	8,391			150			10,559			421
Total gain in pre-tax earnings	$	9		$	—		$	386		$	—