Jointly owned facilities (Tables)

12 Months Ended

Dec. 31, 2012

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:

	2012		2011
	(In thousands)
Big Stone Station:
Utility plant in service	$	63,146	$	63,715
Less accumulated depreciation	40,859		42,475
	$	22,287	$	21,240
Coyote Station:
Utility plant in service	$	135,073	$	131,719
Less accumulated depreciation	87,524		86,788
	$	47,549	$	44,931
Wygen III:
Utility plant in service	$	63,462	$	63,300
Less accumulated depreciation	3,368		2,106
	$	60,094	$	61,194