Segment Information

3 Months Ended

Mar. 31, 2015

Segment Reporting [Abstract]

Segment Information [Text Block]

4. SEGMENT INFORMATION

We primarily operate in two reportable business segments: local gas distribution and gas storage. We also have other investments and business activities not specifically related to one of these two reporting segments, which we aggregate and report as other. We refer to our local gas distribution business as the utility, and our gas storage segment and other as non-utility. Our utility segment also includes the utility portion of our Mist underground storage facility in Oregon (Mist) and NWN Gas Reserves, which is a wholly-owned subsidiary of Energy Corp. Our gas storage segment includes NWN Gas Storage, which is a wholly-owned subsidiary of NWN Energy, Gill Ranch, which is a wholly-owned subsidiary of NWN Gas Storage, the non-utility portion of Mist, and all third-party asset management services. Other includes NNG Financial and NWN Energy's equity investment in Trail West Holdings, LLC (TWH), which is pursuing development of a cross-Cascades transmission pipeline project. See Note 4 in our 2014 Form 10-K for further discussion of our segments.

Inter-segment transactions are insignificant. The following table presents summary financial information concerning the reportable segments:

	Three Months Ended March 31,
In thousands	Utility		Gas Storage		Other		Total
2015
Operating revenues	$	256,306	$	5,303	$	56	$	261,665
Depreciation and amortization	18,475		1,636		—		20,111
Income from operations	51,880		1,055		66		53,001
Net income	28,335		114		37		28,486
Capital expenditures	25,809		1,326		—		27,135
Total assets at March 31, 2015	2,696,506		270,992		14,903		2,982,401
2014
Operating revenues	$	285,495	$	7,835	$	56	$	293,386
Depreciation and amortization	17,967		1,622		—		19,589
Income from operations	71,457		3,553		18		75,028
Net income	36,019		1,627		238		37,884
Capital expenditures	25,350		238		—		25,588
Total assets at March 31, 2014	2,506,930		307,055		16,399		2,830,384
Total assets at December 31, 2014	$	2,775,011	$	273,813	$	16,121	$	3,064,945

Utility Margin

Utility margin is a financial measure consisting of utility operating revenues, which are reduced by revenue taxes and the associated cost of gas. The cost of gas purchased for utility customers is generally a pass-through cost in the amount of revenues billed to regulated utility customers. By subtracting costs of gas from utility operating revenues, utility margin provides a key metric used by our chief operating decision maker in assessing the performance of the utility segment. The gas storage segment and other emphasize growth in operating revenues as opposed to margin because they do not incur a product cost (i.e. cost of gas sold) like the utility and, therefore, use operating revenues and net income to assess performance.

The following table presents additional segment information concerning utility margin:

	Three Months Ended March 31,
In thousands	2015		2014
Utility margin calculation:
Utility operating revenues	$	256,306	$	285,495
Less: Utility cost of gas	125,705		155,201
Utility margin	$	130,601	$	130,294