Components of Impairment Charges (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net Write-Offs [Line Items]
Impairment charges		$ 2	$ 20	$ 43
Contract-Based Intangible Assets [Member]
Net Write-Offs [Line Items]
Impairment charges	[1]			$ 43
Pittsfield [Member] | Contract-Based Intangible Assets [Member]
Net Write-Offs [Line Items]
Impairment charges		$ 13
EfW Joint Venture [Member] [Member]
Net Write-Offs [Line Items]
Impairment charges			$ 3

[1] During the year ended December 31, 2016, we recorded a non-cash impairment charge of $13 million, pre-tax, related to the previously planned closure of our Pittsfield EfW facility which we now continue to operate. Such amount was calculated based on the estimated liquidation value of the tangible equipment utilizing Level 3 inputs. We are party to a joint venture that was formed to recover and recycle metals from EfW ash monofills in North America. During the year ended December 31, 2016, due to operational difficulties and the decline in the scrap metal market, a valuation of the entity was conducted. As a result, we recorded a net impairment of our investment in this joint venture of $3 million, pre-tax, which represents our portion of the carrying value of the entity in excess of the fair value. Such amount was calculated based on the estimated liquidation value of the tangible equipment utilizing Level 3 inputs.