Commitments and Contingencies - Quarter (Details) $ in Millions	3 Months Ended	9 Months Ended
	Mar. 31, 2020 USD ($)	Sep. 30, 2021 USD ($) site item	Dec. 31, 2020 USD ($)
Commitments And Contingencies [Line Items]
Number of landfills adjacent to or near homeowners' properties with agreements guaranteeing market value | item		18
Environmental remediation reasonably possible additional losses high estimate		$ 135
Environmental remediation liabilities		$ 216
Number of sites listed on the EPA's NPL for which we have been notified we are a PRP | site		73
Number of owned sites listed on the EPA's NPL for which we have been notified we are a PRP | site		14
Number of non-owned sites listed on the EPA's NPL for which we have been notified we are a PRP | site		59
Dollar threshold for environmental matters requiring disclosure under item 103 of the SEC's Regulation S-K		$ 1
Workforce covered by collective bargaining (as a percent)		20.00%
Expected time of completion of IRS audits		18 months
San Jacinto Waste Pits [Member]
Commitments And Contingencies [Line Items]
Environmental remediation liabilities		$ 53	$ 55
Withdrawal from Multiemployer Pension Plans [Member]
Commitments And Contingencies [Line Items]
Charge to "Operating" expenses	$ 3
Revolving Credit Facility [Member]
Commitments And Contingencies [Line Items]
Credit Facility, aggregate capacity		$ 3,500