Rate Matters (Details) (Electric Rate Case [Member], Federal Energy Regulatory Commission (FERC) [Member], USD $) In Millions, unless otherwise specified	Apr. 30, 2012
Electric Rate Case [Member] | Federal Energy Regulatory Commission (FERC) [Member]
Rate Matters [Abstract]
Entity's base percent return on equity charged to Golden Spread Electric Cooperative, Inc. through production formula rate (in hundredths)	10.25%
Entity's base percent return on equity charged to Golden Spread Electric Cooperative, Inc. through transmission formula rate (in hundredths)	10.77%
Entity's base return on equity alleged to be appropriate by Golden Spread Electric Cooperative, Inc. (in hundredths)	9.15%
Golden Spread Electric Cooperative, Inc.'s original requested amount of increase (decrease) to existing rates	$ (3.3)
Entity's basis point incentive added to base return on equity for transmission formula rate (in hundredths)	0.50%