Derivative Instruments (Tables)

3 Months Ended

Mar. 31, 2017

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 March 31, 2017 that is expected to settle or mature each year.

Year	Natural Gas Swaps (MMBTUs) (in millions)
2017	20.38
2018	20.91
2019	14.31
2020	10.99
2021	4.69
2022	.02
Total	71.30

Schedule of costs to be amortized and collected in rates over the life of the associated debt

	Balance Sheet Location		Fair Value
			2017		2016
			(dollars in thousands)
Not designated as hedge:
Assets:
Natural gas swaps	Other current assets	$	8,917	$	13,833
Natural gas swaps	Other deferred charges	$	144	$	3,289
Liabilities:
Natural gas swaps	Other current liabilities	$	271	$	54
Natural gas swaps	Other deferred credits	$	3,822	$	1,977

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

	Statement of Revenues and Expenses		Three months ended March 31,
	Location		2017			2016
			(dollars in thousands)
Not Designated as hedges:
Natural Gas Swaps	Fuel	$	840		$	11
Natural Gas Swaps	Fuel		(744	)		(4,228	)
		$	96		$	(4,217	)

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

	Balance Sheet Location		2017			2016
			(dollars in thousands)
Not designated as hedges:
Natural gas swaps	Regulatory asset	$	(1,837	)	$	(62	)
Natural gas swaps	Regulatory liability		6,805			15,152
Interest rate options	Regulatory asset		—			(5,788	)
Total not designated as hedges		$	4,968		$	9,302

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

		Gross Amounts of Recognized Assets (Liabilities)		Gross Amounts offset on the Balance Sheet			Net Amounts of Assets Presented on the Balance Sheet
		(dollars in thousands)
March 31, 2017
Natural gas swaps	$	4,968	$	—		$	4,968
December 31, 2016
Natural gas swaps	$	15,090	$	—		$	15,090
Interest rate options	$	5,788	$	(5,788	)	$	—