Derivative Instruments (Tables)

3 Months Ended

Mar. 31, 2018

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Notional Amounts of Outstanding Derivative Positions

The following table presents the absolute notional amounts related to open positions on our derivative instruments:

	March 31,				December 31,
In thousands	2018		2017		2017
Natural gas (in therms):
Financial	326,080		382,850		429,100
Physical	420,200		368,700		520,268
Foreign exchange	$	7,611	$	6,629	$	7,669

Income Statement Presentation of Derivative Instruments

The following table reflects the income statement presentation for the unrealized gains and losses from our derivative instruments:

	Three Months Ended March 31,
	2018						2017
In thousands	Natural gas commodity			Foreign exchange			Natural gas commodity			Foreign exchange
Benefit (expense) to cost of gas	$	(5,747	)	$	(154	)	$	(13,094	)	$	26
Operating expenses	(227		)	—			(1,226		)	—
Amounts deferred to regulatory accounts on balance sheet	5,895			154			13,893			(26		)
Total gain (loss) in pre-tax earnings	$	(79	)	$	—		$	(427	)	$	—

Table of Estimated Collateral Calls Table

Based upon current commodity financial swap and option contracts outstanding, which reflect unrealized losses of $19.5 million at March 31, 2018, we have estimated the level of collateral demands, with and without potential adequate assurance calls, using current gas prices and various credit downgrade rating scenarios for NW Natural as follows:

			Credit Rating Downgrade Scenarios
In thousands	(Current Ratings) A+/A3		BBB+/Baa1		BBB/Baa2		BBB-/Baa3			Speculative
With Adequate Assurance Calls	$	—	$	—	$	—	$	(8,851	)	$	(30,172	)
Without Adequate Assurance Calls	—		—		—		(7,112		)	(18,433		)