Amount of increase in the fair value of derivatives recognized in the income statement.

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Unrealized and Realized Gain/Loss (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Financial [Member]
Derivative [Line Items]
Derivative, Gain on Derivative			$ 9,200
Derivative, Loss on Derivative	$ (1,100)	$ (1,900)	(15,600)
Northwest Holdings and Northwest Natural [Member] \| Natural gas commodity
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	(291)	98	(7)	$ 43
Northwest Holdings and Northwest Natural [Member] \| Foreign exchange
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	0	0	0	0
Northwest Holdings and Northwest Natural [Member] \| Benefit (expense) to cost of gas \| Natural gas commodity
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	(2,391)	4,473	(4,255)	1,384
Northwest Holdings and Northwest Natural [Member] \| Benefit (expense) to cost of gas \| Foreign exchange
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	133	(210)	(24)	0
Northwest Holdings and Northwest Natural [Member] \| Sales [Member] \| Natural gas commodity
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	(2,002)	286	(36)	122
Northwest Holdings and Northwest Natural [Member] \| Sales [Member] \| Foreign exchange
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	0	0	0	0
Deferred Derivative Gain (Loss) [Member] \| Northwest Holdings and Northwest Natural [Member] \| Natural gas commodity
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	4,102	4,285	4,284	1,305
Deferred Derivative Gain (Loss) [Member] \| Northwest Holdings and Northwest Natural [Member] \| Foreign exchange
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	$ (133)	$ 210	$ 24	$ 0