Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
Current assets:
Cash and cash equivalents	$ 12,817	$ 12,633	$ 11,215
Accounts receivable	93,617	66,970	77,897
Accrued unbilled revenue	36,147	57,827	38,752
Allowance for uncollectible accounts	(1,301)	(977)	(1,112)
Regulatory assets	46,317	41,930	45,900
Derivative instruments	7,890	9,001	1,130
Inventories	19,540	44,149	34,399
Gas reserves	16,157	16,647	15,124
Income Taxes Receivable, Current	6,000	6,000	0
Other current assets	20,293	28,472	16,877
Discontinued operations - current assets	14,632	13,269	1,512
Total current assets	272,109	295,921	241,694
Non-current assets:
Property, plant, and equipment	3,439,460	3,414,490	3,251,075
Less: Accumulated depreciation	1,005,117	993,118	972,773
Property, Plant and Equipment, Net	2,434,343	2,421,372	2,278,302
Gas reserves	61,907	66,197	80,560
Regulatory assets	327,194	371,786	343,037
Derivative instruments	541	725	1,148
Other investments	63,829	63,558	66,709
Operating lease right of use asset	6,163	0	0
Goodwill	8,954	8,954	0
Other non-current assets	16,077	14,149	7,030
Discontinued operations - non-current assets	0	0	10,859
Total non-current assets	2,919,008	2,946,741	2,787,645
Total assets	3,191,117	3,242,662	3,029,339
Current liabilities:
Short-term debt	176,391	217,620	50,000
Current maturities of long-term debt	104,158	29,989	74,785
Accounts payable	103,207	115,878	77,860
Taxes accrued	11,004	11,023	12,018
Interest accrued	9,233	7,306	9,262
Regulatory liabilities	46,770	47,436	34,946
Derivative instruments	2,845	12,381	17,607
Operating lease liabilities	4,656	0	0
Other current liabilities	54,543	54,492	39,166
Discontinued operations current liabilities	13,282	12,959	1,209
Total current liabilities	526,089	509,084	316,853
Long-term debt	632,484	706,247	683,497
Deferred credits and other non-current liabilities:
Deferred tax liabilities	293,662	280,463	283,129
Regulatory liabilities	600,698	611,560	600,442
Pension and other postretirement benefit liabilities	220,732	221,886	221,732
Derivative instruments	1,161	3,025	2,355
Operating lease liabilities	1,495	0	0
Other non-current liabilities	120,569	147,763	137,147
Discontinued operations non-current liabilities	0	0	11,979
Discontinued operations non-current liabilities			12,400
Total deferred credits and other non-current liabilities	1,238,317	1,264,697	1,256,784
Commitments and contingencies (see Note 16 and Note 17)
Equity:
Common stock	459,932	457,640	450,408
Retained earnings	342,734	312,182	330,081
Accumulated other comprehensive loss	(8,439)	(7,188)	(8,284)
Total equity	794,227	762,634	772,205
Total liabilities and equity	3,191,117	3,242,662	3,029,339
Northwest Natural Gas Company [Member]
Current assets:
Cash and cash equivalents	6,833	7,947	10,904
Accounts receivable	93,502	66,824	77,898
Accrued unbilled revenue	36,085	57,773	38,752
Receivables from affiliates	4,247	4,166	422
Allowance for uncollectible accounts	(1,300)	(975)	(1,113)
Regulatory assets	46,317	41,930	45,900
Derivative instruments	7,890	9,001	1,130
Inventories	19,528	44,126	34,399
Gas reserves	16,157	16,647	15,124
Other current assets	19,474	25,347	16,821
Discontinued operations - current assets	0	0	5,731
Total current assets	248,733	272,786	245,968
Non-current assets:
Property, plant, and equipment	3,435,304	3,410,439	3,250,700
Less: Accumulated depreciation	1,004,812	992,855	972,573
Property, Plant and Equipment, Net	2,430,492	2,417,584	2,278,127
Gas reserves	61,907	66,197	80,560
Regulatory assets	327,194	371,786	343,037
Derivative instruments	541	725	1,148
Other investments	50,212	49,922	53,018
Operating lease right of use asset	5,903	0	0
Other non-current assets	15,646	13,736	7,017
Discontinued operations - non-current assets	0	0	24,738
Total non-current assets	2,891,895	2,919,950	2,787,645
Total assets	3,140,628	3,192,736	3,033,613
Current liabilities:
Short-term debt	176,300	217,500	50,000
Current maturities of long-term debt	104,084	29,989	74,785
Accounts payable	102,232	114,937	77,590
Payables to affiliates	1,385	523	3,613
Taxes accrued	10,869	10,990	11,984
Interest accrued	9,225	7,273	9,262
Regulatory liabilities	46,770	47,436	34,946
Derivative instruments	2,845	12,381	17,607
Operating lease liabilities	4,477	0	0
Other current liabilities	53,155	53,027	39,180
Discontinued operations current liabilities	0	0	2,160
Total current liabilities	511,342	494,056	321,127
Long-term debt	630,370	704,134	683,497
Deferred credits and other non-current liabilities:
Deferred tax liabilities	307,704	294,739	299,526
Regulatory liabilities	600,698	611,560	600,442
Pension and other postretirement benefit liabilities	220,732	221,886	221,732
Derivative instruments	1,161	3,025	2,355
Operating lease liabilities	1,413	0	0
Other non-current liabilities	120,465	147,668	137,059
Discontinued operations non-current liabilities	0	0	4,330
Total deferred credits and other non-current liabilities	1,252,173	1,278,878	1,256,784
Equity:
Common stock	226,452	226,452	450,408
Retained earnings	528,730	496,404	330,081
Accumulated other comprehensive loss	(8,439)	(7,188)	(8,284)
Total equity	746,743	715,668	772,205
Total liabilities and equity	$ 3,140,628	$ 3,192,736	$ 3,033,613