Property, Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2012

Property, Plant and Equipment [Abstract]

Major classifications of property, plant and equipment

The following table presents the major classifications of our property, plant and equipment (in thousands):



	Estimated Useful Life	December 31,
	Estimated Useful Life	2012			2011
	(years)	(in thousands)
Land, land rights and easements	49 – 105	$	72,550		$	58,197
Building and improvements	26 – 71	145,989			137,762
Transmission, distribution, and storage	10 – 79	2,339,111			2,225,704
Generation	26 – 46	506,017			415,042
Plant acquisition adjustment	34	204,754			204,754
Other	2 - 40	259,308			242,117
Construction work in process	–—	121,360			78,169
		3,649,089			3,361,745
Less accumulated depreciation		(1,213,499		)	(1,148,478		)
		$	2,435,590		$	2,213,267

Schedule of jointly owned utility plants

Information relating to our ownership interest in these facilities is as follows (in thousands):



	Big Stone (SD)			Neal #4 (IA)			Coyote (ND)			Colstrip Unit 4 (MT)
December 31, 2012
Ownership percentages	23.4		%	8.7		%	10.0		%	30.0		%
Plant in service	$	61,084		$	30,009		$	46,188		$	290,607
Accumulated depreciation	38,021			23,994			30,655			67,534
December 31, 2011
Ownership percentages	23.4		%	8.7		%	10.0		%	30.0		%
Plant in service	$	58,383		$	29,991		$	45,066		$	287,462
Accumulated depreciation	39,246			23,046			29,740			59,586

- Definition

Tabular disclosure of the useful life and salvage value of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale. Examples include land, buildings, machinery and equipment, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software.

+ References+ Details

- Definition

Tabular disclosure of proportionate interests in jointly owned utility plants. Includes the amount of plants in service, the accumulated provision for depreciation (if available), the amount of plants under construction, and the proportionate share. The amounts presented may be further subdivided to show amounts applicable to plant subcategories (for example, production, transmission, distribution). Includes statements that the amounts represent the utility's share in each joint plant and that it must provide its own financing. Information concerning two or more generating plants on the same site may be combined. States that the utility's share of direct expenses of the joint plants is included in the corresponding operating expenses on its income statement (for example, fuel, maintenance of plant, other operating expense). If the share of direct expenses is charged to purchased power, then disclose the amount so charged and the proportionate amounts charged to specific operating expenses on the records maintained for the joint plants.

+ References+ Details