Valuation Allowances and Reserves (Tables)

12 Months Ended

Dec. 31, 2021

Entity Information [Line Items]

Summary of Valuation Allowance

NORTHWEST NATURAL HOLDING COMPANY

SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS AND RESERVES

COLUMN A	COLUMN B		COLUMN C				COLUMN D		COLUMN E
			Additions				Deductions
In thousands (year ended December 31)	Balance at beginning of period		Charged to costs and expenses		Charged to other accounts		Net write-offs		Balance at end of period
2021
Reserves deducted in balance sheet from assets to which they apply:
Allowance for uncollectible accounts	$	3,219	$	724	$	(219)	$	1,706	$	2,018
2020
Reserves deducted in balance sheet from assets to which they apply:
Allowance for uncollectible accounts	$	673	$	890	$	2,333	$	677	$	3,219
2019
Reserves deducted in balance sheet from assets to which they apply:
Allowance for uncollectible accounts	$	977	$	450	$	—	$	754	$	673

Northwest Natural Gas Company [Member]

Entity Information [Line Items]

Summary of Valuation Allowance

NORTHWEST NATURAL GAS COMPANY

SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS AND RESERVES

COLUMN A	COLUMN B		COLUMN C				COLUMN D		COLUMN E
			Additions				Deductions
In thousands (year ended December 31)	Balance at beginning of period		Charged to costs and expenses		Charged to other accounts		Net write-offs		Balance at end of period
2021
Reserves deducted in balance sheet from assets to which they apply:
Allowance for uncollectible accounts	$	3,107	$	780	$	(219)	$	1,706	$	1,962
2020
Reserves deducted in balance sheet from assets to which they apply:
Allowance for uncollectible accounts	$	672	$	779	$	2,333	$	677	$	3,107
2019
Reserves deducted in balance sheet from assets to which they apply:
Allowance for uncollectible accounts	$	975	$	450	$	—	$	753	$	672