Commitments and Contingencies - Additional Information (Detail) (USD $)	12 Months Ended				1 Months Ended			1 Months Ended
	Oct. 31, 2013	Oct. 31, 2013 Maximum	Oct. 31, 2013 Claims Incurred After November 1, 2002 Maximum	Oct. 31, 2013 Effective date starting after October 31, 2013	Jul. 31, 2012 Augustus Claim	Feb. 08, 2012 Augustus	Oct. 31, 2013 Augustus	Jan. 14, 2013 Augustus Motion against others	Jul. 31, 2012 Augustus Motion against others	Apr. 11, 2013 Bojorquez	May 17, 2012 Bojorquez
Loss Contingencies [Line Items]
Surety bonds	$ 332,500,000			$ 1,400,000
Total letters of credit	100,600,000
Total energy savings guarantees for certain customers	31,400,000
Guarantee term for certain customers	Through 2027
Deductible directors' and officers' insurance		5,000,000	1,000,000
Loss contingency amount accrued for probable losses	2,200,000
Amount of reasonably possible losses, Minimum	1,000,000
Amount of reasonably possible losses, Maximum	98,100,000
Loss Contingency, estimate of possible loss							94,200,000
Damages sought amount						103,100,000		4,500,000	12,400,000
Payment awarded to plaintiffs					$ 89,700,000					$ 2,500,000	$ 800,000
Number of claim suit filed					3