Derivative Instruments - Additional Information (Detail) MW in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) MW BTU	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU	1,000,000.0
Payments related to cash conversion option	$ 132	$ 0	$ 0
Derivative, Nonmonetary Notional Amount | MW	3.5
Payments for (Proceeds from) Hedge, Investing Activities	$ 0	0
Line of Credit Facility, Maximum Borrowing Capacity	1,200
Liabilities, Current	1,037	418
Dublin EfW Facility [Member] | Term Loan [Member]
Derivative [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity				$ 300
Energy Hedges [Member]
Derivative [Line Items]
Proceeds from Hedge, Investing Activities	17	32
Derivative Liability, Noncurrent	$ 1
Fiscal Year 2018 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | MW	2.9
Fiscal Year 2019 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | MW	0.6
Fair Value, Inputs, Level 2 [Member] | Energy Hedges [Member]
Derivative [Line Items]
Derivative Liability	$ 5	1
Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative Liability	0	20
Sanfeng Environmental [Member]
Derivative [Line Items]
Derivative, Notional Amount		100
Proceeds from Sales of Assets, Investing Activities		105
Proceeds from Hedge, Investing Activities	5
Derivative Asset, Current	0	0
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Energy Hedges [Member]
Derivative [Line Items]
Derivative Liability, Current	4
Derivative Asset		2
Derivative Asset, Current		3
Derivative Liability, Noncurrent		1
Derivative Liability	(5)
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative Liability, Current		2
Derivative Liability, Noncurrent		18
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Energy Hedges [Member] | Energy Hedges [Member]
Derivative [Line Items]
Derivative Asset, Current	0	3
Assets Held-for-sale [Member] | Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative Liability	7	$ 0
Loss on Cash Flow Hedge Ineffectiveness	$ 1