Organization and Summary of Significant Accounting Policies - Additional Information (Details) T in Millions, MW in Millions, $ in Millions			3 Months Ended								12 Months Ended
		Oct. 01, 2019 report	Dec. 31, 2019 USD ($) MW T Facility	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2019 USD ($) MW T Segment Facility shares	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($) shares	Jan. 01, 2019 USD ($)	Jan. 01, 2017 USD ($)	Dec. 31, 2016 USD ($)
Organization And Summary Of Significant Accounting Policies [Line Items]
Asset Retirement Obligation			$ 26				$ 29				$ 26	$ 29	$ 26
Stock Repurchased During Period, Shares | shares											0	0	0
Right of use assets			46								$ 46
Operating lease liability			$ 52								52
Impairment of Long-Lived Assets to be Disposed of											2	$ 63	$ 2
Cost of Goods and Services Sold											1,371	1,321	1,271
Impairment of Intangible Assets, Finite-lived											$ 0	22	0
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount			5.00%								5.00%
Intangible Assets, Net (Excluding Goodwill)			$ 258				279				$ 258	279
Cash and cash equivalents			$ 37				58				37	58	46
Net Cash Provided by (Used in) Operating Activities											226	238	242
Defined Contribution Plan, Cost											$ 20	18	18
Organization (additional details) [Abstract]
Annual processing capacity | T			21								21
Number of Operate and/or ownership positions in energy generation facilities | Facility			41								41
Annual generation capacity of megawatt hours | MW			10								10
Number of Reportable Segments | Segment											1
Restricted Funds Held in Trust [Abstract]
Restricted funds held in trust			$ 18				39				$ 18	39	43
Restricted funds held in trust, noncurrent			8				8				8	8	28
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations			63				105				63	105	194			$ 194
Deferred Revenue [Abstract]
Deferred Revenue, Current			12				10				12	10
Property, Plant and Equipment [Abstract]
Land			20				26				20	26
Facilities And Equipment Gross			4,463				4,367				4,463	4,367
Landfill Gross			78				75				78	75
Construction in Progress, Gross			58				71				58	71
Property, Plant and Equipment, Gross			4,619				4,539				4,619	4,539
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment			(2,168)				(2,025)				(2,168)	(2,025)
Property, plant and equipment, net			2,451				2,514				2,451	2,514
Depreciation											201	199	197
Capital Expenditures Incurred but Not yet Paid											6	37	18
Asset Retirement Obligation [Abstract]
Accretion expense											2	3
Net change	[1]										(3)	0
Reclassification to assets held for sale											(2)	0
Less: current portion			(4)				(5)				(4)	(5)
Noncurrent asset retirement obligation			22				24				22	24
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive (loss) income			(35)				(33)				(35)	(33)	(55)	$ (32)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax											(3)	(7)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax												(29)
Other Comprehensive Income (Loss), Net of Tax											(3)	22
Net (loss) gain on intra-entity foreign currency transactions											(5)	(2)	19
Net gain on sale of business and investments											49	217	(6)
(Loss) income before income tax benefit and equity in net income from unconsolidated investments											(3)	117	(135)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax												29
Accounting Changes [Abstract]
Retained Earnings (Accumulated Deficit)			(460)				(334)				(460)	(334)
Cumulative effect change in accounting															$ 11
Deferred income taxes			372				378				372	378
Income Tax Expense (Benefit)											(7)	(29)	(191)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest			12	$ 14	$ (21)	$ 5	9	$ (27)	$ (31)	$ 201	10	152	57
Net Cash Provided by (Used in) Investing Activities											(145)	(139)	(289)
Net Cash Provided by (Used in) Financing Activities											(122)	(189)	40
Goodwill			321				321				321	321	313
Number of Reporting Units | report		2
Accounting Standards Update 2016-02 [Member]
Organization And Summary Of Significant Accounting Policies [Line Items]
Right of use assets														57
Operating lease liability														62
Accumulated Other Comprehensive Loss
Accounting Changes [Abstract]
Cumulative effect change in accounting															$ 10
Accumulated Other Comprehensive Loss | Accounting Standards Update 2018-02 [Member]
Accounting Changes [Abstract]
Cumulative effect change in accounting														1
Accumulated Other Comprehensive Loss | Accounting Standards Update 2018-02 [Member]
Accounting Changes [Abstract]
Cumulative effect change in accounting														1
Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive (loss) income			(24)				(19)				(24)	(19)	(17)	(19)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax											(5)	(4)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax												(2)
Other Comprehensive Income (Loss), Net of Tax											(5)	(2)
Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest [Member] | Accounting Standards Update 2018-02 [Member]
Accounting Changes [Abstract]
Cumulative effect change in accounting														0
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Including Portion Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive (loss) income			3				2				3	2	2	3
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax											0	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax												0
Other Comprehensive Income (Loss), Net of Tax											0	0
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Including Portion Attributable to Noncontrolling Interest [Member] | Accounting Standards Update 2018-02 [Member]
Accounting Changes [Abstract]
Cumulative effect change in accounting														1
Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive (loss) income			(8)				(12)				(8)	(12)	(33)	(12)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax											4	(6)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax												(27)
Other Comprehensive Income (Loss), Net of Tax											4	21
Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest [Member] | Accounting Standards Update 2018-02 [Member]
Accounting Changes [Abstract]
Cumulative effect change in accounting														0
Unrealizedlossonintraentityforeigncurrencytransactions [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive (loss) income			(6)				(4)				(6)	(4)	(7)	(4)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax											(2)	3
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax												0
Other Comprehensive Income (Loss), Net of Tax											$ (2)	3
Unrealizedlossonintraentityforeigncurrencytransactions [Member] | Accounting Standards Update 2018-02 [Member]
Accounting Changes [Abstract]
Cumulative effect change in accounting														$ 0
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest [Member]
Accounting Changes [Abstract]
Income Tax Expense (Benefit)												0
Minimum [Member] | Computer Equipment [Member]
Property, Plant and Equipment [Abstract]
Original useful lives for equipment											3 years
Maximum [Member] | Equipment [Member]
Property, Plant and Equipment [Abstract]
Original useful lives for equipment											50 years
Pass through costs [Member]
Organization And Summary Of Significant Accounting Policies [Line Items]
Cost of Goods and Services Sold											$ 57	57	$ 59
CES
Accounting Changes [Abstract]
Goodwill			$ 46								$ 46
Measurement Input, Discount Rate [Member] | CES
Accounting Changes [Abstract]
Goodwill, Measurement Input			10.00%								10.00%
Goodwill Impairment Trigger			10.80%								10.80%
Goodwill Fluctuation Threshold			0.80%								0.80%
Long Term Terminal Growth Rate [Member] | CES
Accounting Changes [Abstract]
Goodwill, Measurement Input			2.50%								2.50%
Goodwill Impairment Trigger			1.30%								1.30%
Goodwill Fluctuation Threshold			1.20%								1.20%
Other Funds [Member]
Restricted Funds Held in Trust [Abstract]
Restricted funds held in trust			$ 13				19				$ 13	19
Restricted funds held in trust, noncurrent			8				8				8	8
Revenue Funds [Member]
Restricted Funds Held in Trust [Abstract]
Restricted funds held in trust			3				4				3	4
Restricted funds held in trust, noncurrent			0				0				0	0
Debt Service Funds [Member]
Restricted Funds Held in Trust [Abstract]
Restricted funds held in trust			2				16				2	16
Restricted funds held in trust, noncurrent			0				0				0	0
Debt Service Funds [Member] | Principal Amount [Member]
Restricted Funds Held in Trust [Abstract]
Restricted funds held in trust			2				16				2	16
Restricted funds held in trust, noncurrent			0				0				0	0
Debt Service Funds [Member] | Interest Amount [Member]
Restricted Funds Held in Trust [Abstract]
Restricted funds held in trust			0				0				0	0
Restricted funds held in trust, noncurrent			$ 0				$ 0				$ 0	$ 0

[1] Comprised primarily of expenditures and settlements of the asset retirement obligation liability, net revisions based on current estimates of the liability and revised expected cash flows and life of the liability.