Derivative Instruments (Tables)

6 Months Ended

Jun. 30, 2015

Derivative Instruments

Schedule of volume activity of natural gas derivatives that is expected to settle or mature each year

The following table reflects the volume activity of our natural gas derivatives as of June 30, 2015 that is expected to settle or mature each year:

Year	Natural Gas Swaps (MMBTUs) (in millions)
2015	12.9
2016	13.8
2017	3.2
Total	29.9

Schedule of remaining notional amount of forecasted debt issuances hedged in each year with LIBOR swaptions

The following table reflects the remaining notional amount of forecasted debt issuances we have hedged in each year with LIBOR swaptions as of June 30, 2015.

Year		LIBOR Swaption Notional Dollar Amount (in thousands)
2015	$	238,818
2016		310,533
2017		80,169
Total	$	629,520

Schedule of fair value of derivative instruments and their effect on consolidated balance sheets

	Balance Sheet Location		Fair Value
			2015		2014
			(dollars in thousands)
Not designated as hedges:
Assets:
Interest rate options	Other deferred charges	$	4,715	$	4,371
Liabilities:
Natural gas swaps	Other current liabilities	$	10,198	$	13,418
Natural gas swaps	Other deferred credits		5,744		5,496

Schedule of the realized gains and (losses) on derivative instruments recognized in margin

	Statement of Revenues and Expenses		Three months ended June 30,					Six months ended June 30,
	Location		2015			2014		2015			2014
			(dollars in thousands)
Not Designated as hedges:
Natural Gas Swaps	Fuel	$	181		$	956	$	181		$	1,236
Natural Gas Swaps	Fuel		(3,248	)		—		(8,775	)		—
		$	(3,067	)	$	956	$	(8,594	)	$	1,236

Schedule of unrealized gains and (losses) on derivative instruments deferred on the balance sheet

	Balance Sheet Location		2015			2014
			(dollars in thousands)
Not designated as hedges:
Natural gas swaps	Regulatory asset	$	(15,942	)	$	(18,914	)
Interest rate options	Regulatory asset		(36,323	)		(49,232	)
Total not designated as hedges		$	(52,265	)	$	(68,146	)

Schedule of gross amounts of derivatives and their related offset amounts as permitted by their respective master netting agreements and obligation to return cash collateral

		Gross Amounts of Recognized Assets (Liabilities)			Gross Amounts offset on the Balance Sheet			Cash Collateral		Net Amounts of Assets Presented on the Balance Sheet
		(dollars in thousands)
June 30, 2015
Assets:
Natural gas swaps	$	(15,942	)	$	—		$	—	$	(15,942	)
Interest rate options	$	41,038		$	(36,323	)	$	—	$	4,715
December 31, 2014
Assets:
Natural gas swaps	$	(18,914	)	$	—		$	—	$	(18,914	)
Interest rate options	$	53,603		$	(49,232	)	$	—	$	4,371