Valuation Allowances and Reserves

12 Months Ended

Dec. 31, 2011

Schedule Of Valuation And Qualifying Accounts Disclosure [Abstract]

Schedule of Valuation and Qualifying Accounts Disclosure [Text Block]

NORTHWEST NATURAL GAS COMPANY
SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS AND RESERVES
COLUMN A	COLUMN B		COLUMN C				COLUMN D		COLUMN E
			Additions				Deductions
	Balance at		Charged to		Charged to				Balance at
	beginning		costs and		other		Net		end of
Thousands (year ended Dec. 31)	of period		expenses		accounts		Write-offs		period
2011
Reserves deducted in balance sheet from assets to which they apply:
Allowance for uncollectible accounts	$	2,950	$	1,919	$	-	$	1,974	$	2,895
2010
Reserves deducted in balance sheet from assets to which they apply:
Allowance for uncollectible accounts	$	3,125	$	1,717	$	-	$	1,892	$	2,950
2009
Reserves deducted in balance sheet from assets to which they apply:
Allowance for uncollectible accounts	$	2,927	$	4,201	$	-	$	4,003	$	3,125