Acquisitions - Additional Information (Detail) (USD $)	4 Months Ended			0 Months Ended		0 Months Ended		3 Months Ended	0 Months Ended
	Jan. 31, 2014 Plainfield Renewal Energy Holdings LLC	Oct. 11, 2013 Plainfield Renewal Energy Holdings LLC MW	Jan. 31, 2014 maxIT Healthcare Holdings, Inc.	Oct. 11, 2013 Connecticut Light and Power Plainfield Renewal Energy Holdings LLC	Oct. 11, 2013 Plainfield Renewal Energy Holdings LLC	Dec. 16, 2013 Carlyle Group Plainfield Renewal Energy Holdings LLC	Oct. 11, 2013 Secured Debt Carlyle Group Plainfield Renewal Energy Holdings LLC note	Nov. 01, 2013 Receivable from PRE Holdings Plainfield Renewal Energy Holdings LLC	Oct. 11, 2013 Minimum Plainfield Renewal Energy Holdings LLC	Oct. 11, 2013 Maximum Plainfield Renewal Energy Holdings LLC	Jan. 31, 2014 November 2015 or the successful sale of the plant Plainfield Renewal Energy Holdings LLC	Jan. 31, 2014 Achievement of Milestones Plainfield Renewal Energy Holdings LLC
Business Acquisition [Line Items]
Percentage of ownership		100.00%
Capacity of power plant		37.5
Percentage of power to be purchased				80.00%
Term of agreement				15 years
Fuel supply agreement, term									5 years	15 years
Receivable due from Plainfield					$ 137,000,000
Number of debt instruments financed by Carlyle Grp							2
Senior notes, face amount							148,000,000
Repayment of principal						152,000,000
Repayment of debt						165,000,000
Loss recorded as bad debt								32,000,000
Contingent consideration		6,000,000									2,000,000	3,000,000
Revenue from acquisition	2,000,000
Operating loss	$ 5,000,000
Percent of acquired stock			100.00%