Redeemable Noncontrolling Interests And Subsidiary Acquisitions (Narrative) (Detail) (USD $)	9 Months Ended					12 Months Ended			1 Months Ended			1 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 2012 [Member]	Sep. 30, 2012 2013 [Member]	Sep. 30, 2012 2014 [Member]	Dec. 31, 2011 Prenova [Member]	Nov. 30, 2011 Prenova [Member]	Jan. 31, 2012 LPB Energy Management [Member]	Jan. 31, 2012 LPB Energy Management [Member] Client Backlog [Member]	Jan. 31, 2012 LPB Energy Management [Member] Client Relationships [Member]	Jan. 31, 2012 LPB Energy Management [Member] Internal Use Software [Member]	Jan. 31, 2012 LPB Energy Management [Member] Minimum [Member] Internal Use Software [Member]	Jan. 31, 2012 LPB Energy Management [Member] Maximum [Member] Internal Use Software [Member]	Jan. 31, 2012 Ecova [Member]
Business Acquisition [Line Items]
Redemption rights expiration date	July 31, 2012
Cash paid for acquisition							$ 35,600,000	$ 50,600,000
Assets acquired, accounts receivable								2,500,000
Assets acquired, goodwill								33,500,000
Intangible assets acquired									8,200,000	4,800,000	2,500,000
Estimated amortization period (in years)						9 years			3 years	10 years		3 years	4 years
Borrowings under committed credit agreement														25,000,000
Equity infusion from existing shareholders	28,699,000	21,216,000												20,000,000
Potential for additional purchase price payment			500,000	1,000,000	1,500,000
Contingent liability	$ 400,000