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		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Financial [Member]
Derivative [Line Items]
Derivative, Gain on Derivative				$ 10,400
Derivative, Loss on Derivative	$ (1,100)	$ (900)	$ (3,200)
Northwest Holdings and Northwest Natural [Member] \| Natural gas commodity
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	(127)	629	244	284
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	(5,492)	(5,143)	(149)	1,864
Northwest Holdings and Northwest Natural [Member] \| Benefit (expense) to cost of gas \| Foreign exchange
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	(459)	(246)	7	(157)
Northwest Holdings and Northwest Natural [Member] \| Sales [Member] \| Natural gas commodity
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	(754)	4,333	1,679	1,966
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	6,119	(8,847)	(1,286)	182
Deferred Derivative Gain (Loss) [Member] \| Northwest Holdings and Northwest Natural [Member] \| Foreign exchange
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	$ 459	$ 246	$ (7)	$ 157