Valuation Allowances and Reserves

12 Months Ended

Dec. 31, 2012

Valuation Allowances and Reserves [Abstract]

Schedule of Valuation and Qualifying Accounts [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
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
2012
Reserves deducted in balance sheet from assets to which they apply:
Allowance for uncollectible accounts	$	2,895	$	1,130	$	—	$	1,507	$	2,518
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