Jointly Owned Facilities (Tables)

12 Months Ended

Dec. 31, 2011

Regulated Operations [Abstract]

Company's share of the cost of utility plant in service and related accumulated depreciation for the stations

At December 31, the Company's share of the cost of utility plant in service and related accumulated depreciation for the stations was as follows:

	2011		2010
	(In thousands)
Big Stone Station:
Utility plant in service	$	63,715	$	60,404
Less accumulated depreciation	42,475		41,136
	$	21,240	$	19,268
Coyote Station:
Utility plant in service	$	131,719	$	131,395
Less accumulated depreciation	86,788		84,710
	$	44,931	$	46,685
Wygen III:*
Utility plant in service	$	63,300	$	63,215
Less accumulated depreciation	2,106		838
	$	61,194	$	62,377

* Began commercial operation on April 1, 2010.