Derivative Instruments (Tables)

3 Months Ended

Mar. 31, 2018

Derivative Instruments

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

The following table reflects the notional volume of our natural gas derivatives as of March 31, 2018 that is expected to settle or mature each year:

Year	Natural Gas Swaps (MMBTUs) (in millions)
2018	22.7
2019	20.1
2020	17.0
2021	13.7
2022	8.5
Total	82.0

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 March 31, 2018 and December 31, 2017.

	Balance Sheet Location		Fair Value
			2018		2017
			(dollars in thousands)
Assets:
Natural gas swaps	Other current assets	$	308	$	412
Liabilities:
Natural gas swaps	Other current liabilities	$	836	$	1,575
Natural gas swaps	Other deferred credits	$	6,375	$	5,165

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

	Statement of Revenues and Expenses Location		Three months ended March 31,
			2018			2017
			(dollars in thousands)
Natural Gas Swaps	Fuel	$	1,392		$	840
Natural Gas Swaps	Fuel		(748	)		(744	)
Total		$	644		$	96

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

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

	Balance Sheet Location		2018			2017
			(dollars in thousands)
Natural gas swaps	Regulatory asset	$	(6,903	)	$	(6,328	)
Total		$	(6,903	)	$	(6,328	)