Derivative Instruments (Tables)

9 Months Ended

Sep. 30, 2018

Derivative Instruments

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

	Natural GasSwaps
	(MMBTUs)
Year	(in millions)
2018	4.1
2019	21.9
2020	19.6
2021	17.1
2022	11.5
2023	1.4
Total	75.6

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

The table below reflects the fair value of derivative instruments and their effect on our consolidated balance sheets at September 30, 2018 and December 31, 2017.

	BalanceSheet
	Location	Fair Value
		2018		2017
		(dollars in thousands)
Assets:
Natural gas swaps	Other current assets	$	290	$	412
Liabilities:
Natural gas swaps	Other current liabilities	$	2,440	$	1,575
Natural gas swaps	Other deferred credits	$	12,811	$	5,165

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

	Statement of
	Revenues and	Three months				Nine months
	Expenses	ended				ended
	Location	September 30,				September 30,
		2018		2017		2018		2017
		(dollars in thousands)
Natural Gas Swaps	Fuel	$	863	$	778	$	2,614	$	3,514
Natural Gas Swaps	Fuel		(97)		(678)		(956)		(1,495)
Total		$	766	$	100	$	1,658	$	2,019

Schedule of net unrealized losses on derivative instruments deferred on the balance sheet

The following table presents the net unrealized losses on derivative instruments deferred on the balance sheet at September 30, 2018 and December 31, 2017.

	Balance Sheet
	Location	2018		2017
		(dollars in thousands)
Natural gas swaps	Regulatory asset	$	(14,961)	$	(6,328)
Total		$	(14,961)	$	(6,328)