Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Taxes [Line Items]
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Provisional Income Tax Expense (Benefit)	$ 21
Tax Cuts And Jobs Act Of 2017, Incomplete Accounting, Deferred Tax Asset, Reduction Related to Gross Net Operating Loss	59
Tax Cuts And Jobs Act Of 2017, Incomplete Accounting, Change In Tax Rate, Deferred Tax Asset, Provisional Income Tax Expense	204
Tax Cuts And Jobs Act Of 2017, Incomplete Accounting, Transition Tax For Accumulated Foreign Earnings, Provisional Income Tax Expense	21
Components of Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current Federal Tax Expense (Benefit)	4	$ (2)	$ (91)
Current State and Local Tax Expense (Benefit)	2	6	16
Current Foreign Tax Expense (Benefit)	(1)	(2)	2
Current Income Tax Expense (Benefit)	5	2	(73)
Deferred Federal Income Tax Expense (Benefit)	(204)	28	7
Deferred State and Local Income Tax Expense (Benefit)	(2)	(9)	(11)
Deferred Foreign Income Tax Expense (Benefit)	10	1	(7)
Deferred income taxes	(196)	20	(11)
Income Tax Expense (Benefit)	(191)	22	(84)
Pre-tax income [Abstract]
Income (Loss) from Continuing Operations before Income Taxes, Domestic	(43)	26	6
Income (Loss) from Continuing Operations before Income Taxes, Foreign	(92)	(12)	(34)
(Loss) income before income tax benefit (expense) and equity in net income from unconsolidated investments	$ (135)	$ 14	$ (28)
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Effective income tax rate	(142.00%)	(150.00%)	(302.00%)
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	35.00%
Income Tax Reconciliation, Income Tax Expense (Benefit), at Federal Statutory Income Tax Rate	$ (47)	$ 5	$ (10)
Income Tax Reconciliation, State and Local Income Taxes	(2)	1	1
Income Tax Reconciliation, Change in Deferred Tax Assets Valuation Allowance	31	2	(7)
Income Tax Reconciliation, Other Reconciling Items	4	4	4
Effective Income Tax Rate Reconciliation, Disposition of Asset, Amount	(8)	0	0
Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount	10	4	8
Income Tax Reconciliation, Tax Credits, Research	0	0	(3)
Effective Income Tax Rate Reconciliation, Tax Credit, Investment, Amount	1	(4)	0
Income Tax Reconciliation Uncertain Tax Positions	0	16	(82)
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Other, Amount	1	(1)	1
Income Tax Reconciliation, Other Adjustments	(1)	(5)	4
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	(204)	0	0
Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Amount	21	0	0
Effective Income Tax Rate Reconciliation, Expiration of Non-qualified Stock Options	3	0	0
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Consolidated net operating loss carryforwards	240
Deferred Tax Assets, Operating Loss Carryforwards, State and Local	3
Valuation allowance	(77)	(71)
Components of Deferred Tax Assets and Liabilities [Abstract]
Deferred Tax Assets, Operating Loss Carryforwards	119	143
Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Accrued Liabilities	15	20
Deferred Tax Assets Prepaid Expenses And Accruals	48	71
Deferred Tax Assets Attributable To Pass Through Entities	10	17
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits	2	3
Deferred Tax Assets, Other	3	4
Deferred Tax Assets, Tax Credit Carryforwards	48	55
Deferred Tax Assets, Gross	245	313
Deferred Tax Assets, Net of Valuation Allowance	168	242
Deferred Tax Liabilities Unbilled Receivables	3	3
Deferred Tax Liabilities, Property, Plant and Equipment	538	780
Deferred Tax Liabilities, Intangible Assets	33	36
Deferred Tax Liabilities Attributable To Pass Through Entities	8	22
Deferred Tax Liabilities Accrued Original Issue Discount	4	13
Deferred Tax Liabilities, Derivatives	0	0
Deferred Tax Liabilities, Prepaid Expenses	0	0
Deferred Tax Liabilities, Other	1	5
Deferred Tax Liabilities Gross	587	859
Deferred Tax Liabilities, Net	412	617
Deferred Tax Liabilities, Undistributed Foreign Earnings	0	257
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-based Compensation Cost		26
Deferred Tax Liabilities, Net Including Held For Sale Amounts	419	617
Disclosure Reconciliation Of The Beginning And Ending Amount Of Unrecognized Tax Benefits [Abstract]
Unrecognized Tax Benefits		43	36	$ 133
Unrecognized Tax Benefits, Increases Resulting from Current Period Tax Positions	1	16	12
Unrecognized Tax Benefits, Increases Resulting from Prior Period Tax Positions		4
Unrecognized Tax Benefits, Reductions Resulting from Lapse of Applicable Statute of Limitations	(1)	(3)
Unrecognized Tax Benefits, Decreases Resulting from Prior Period Tax Positions	(2)	(4)	$ (109)
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities		(6)
Payments for Other Taxes	1
Uncertain Tax Positions [Abstract]
Liability for Uncertainty in Income Taxes, Current	48	43
Accrued interest and penalties associated with liabilities for unrecognized tax positions	5	3
Grantor Trusts [Abstract]
Cumulative Effect of New Accounting Principle in Period of Adoption	11			$ (45)
State and Local Jurisdiction [Member]
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Consolidated net operating loss carryforwards	389
Foreign Tax Authority [Member]
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Consolidated net operating loss carryforwards	287
Federal Jurisdiction [Member]
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Valuation allowance	$ (77)
Minimum [Member] | State and Local Jurisdiction [Member]
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2028
Minimum [Member] | Foreign Tax Authority [Member]
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2018
Minimum [Member] | Federal Jurisdiction [Member]
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Other Tax Carryforward, Expiration Dates	Dec. 31, 2024
Maximum [Member] | State and Local Jurisdiction [Member]
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2037
Maximum [Member] | Foreign Tax Authority [Member]
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2037
Maximum [Member] | Federal Jurisdiction [Member]
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Other Tax Carryforward, Expiration Dates	Dec. 31, 2036
2028 [Member]
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Consolidated net operating loss carryforwards	$ 10
2030 [Member]
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Consolidated net operating loss carryforwards	29
2031 [Member]
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Consolidated net operating loss carryforwards	1
2032 [Member]
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Consolidated net operating loss carryforwards	1
2033 [Member]
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Consolidated net operating loss carryforwards	197
2035 [Member]
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Consolidated net operating loss carryforwards	1
2036 [Member]
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Consolidated net operating loss carryforwards	1
Production Type [Member] | Federal Jurisdiction [Member]
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Tax credit carryforwards	47
Research Tax Credit Carryforward [Member] | Federal Jurisdiction [Member]
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Tax credit carryforwards	$ 1
Research Tax Credit Carryforward [Member] | Minimum [Member] | Federal Jurisdiction [Member]
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Other Tax Carryforward, Expiration Dates	Dec. 31, 2027
Research Tax Credit Carryforward [Member] | Maximum [Member] | Federal Jurisdiction [Member]
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Other Tax Carryforward, Expiration Dates	Dec. 31, 2033
Dublin EfW Facility [Member]
Grantor Trusts [Abstract]
Disposal Group, Including Discontinued Operation, Deferred Tax Liabilities	$ 7	$ 0