Subsequent Event - Additional Information (Detail) (Subsequent Event [Member], Wheelabrator [Member], USD $) In Millions, unless otherwise specified	0 Months Ended
	Jul. 25, 2014
Subsequent Event [Member] | Wheelabrator [Member]
Subsequent Event [Line Items]
Sale price of business	$ 1,940
Agreement date	Jul. 25, 2014
Agreement description	On July 25, 2014, the Company signed a definitive Stock Purchase Agreement ("Agreement") to sell our Wheelabrator business to an affiliate of Energy Capital Partners for $1.94 billion in cash, subject to certain post-closing adjustments.