Regulatory Matters (Details) (Tennessee Regulatory Authority [Member], USD $)	3 Months Ended
	Jul. 31, 2012	May 07, 2012	Oct. 31, 2011	Feb. 26, 2010
Tennessee Regulatory Authority [Member]
Schedule Of Regulatory Matters [Line Items]
Proposed Rate Adjustment For Uncollected Franchise Fees				$ 2,900,000
Denial Of Proposed Rate Adjustment For Uncollected Franchise Fees			1,500,000
Denied Franchise Fees Recorded In Operations And Maintenance			1,500,000
Additional Recovery Franchise Fees		500,000
Allowed Franchise Fees Recorded In Operations And Maintenance	$ 500,000