Amount of short-term and long-term debt and lease obligation.

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount, after accumulated amortization, of debt discount (premium).

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Present value of lessee's discounted obligation for lease payments from finance lease.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount of long-term debt and lease obligation, classified as noncurrent.

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Amount of long-term debt and lease obligation, classified as current.

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Debt and Capital Leases - Schedule of Long-term Debt and Capital Leases (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019	May 28, 2019	May 14, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Debt amount	$ 6,042			$ 6,691
Capital leases	1			1
Subtotal long-term debt and capital leases (including current maturities)	6,043			6,692
Less current maturities	(87)			(72)
Less debt issuance costs	(71)			(70)
Discounts	(91)			(101)
Long-term debt and capital leases	5,794			6,449
Recourse Debt
Debt Instrument [Line Items]
Debt amount	5,925			6,523
Recourse Debt \| Senior Notes, due 2024
Debt Instrument [Line Items]
Debt amount	$ 0			733
Interest rate, stated percentage	6.25%
Recourse Debt \| Senior Notes, due 2026
Debt Instrument [Line Items]
Debt amount	$ 1,000			1,000
Interest rate, stated percentage	7.25%
Recourse Debt \| Senior Notes, due 2027
Debt Instrument [Line Items]
Debt amount	$ 1,230			1,230
Interest rate, stated percentage	6.625%
Recourse Debt \| Senior Notes, due 2028
Debt Instrument [Line Items]
Debt amount	$ 821			821
Interest rate, stated percentage	5.75%
Recourse Debt \| Senior Notes, due 2029
Debt Instrument [Line Items]
Debt amount	$ 733			0
Interest rate, stated percentage	5.25%		5.25%
Recourse Debt \| Convertible Senior Notes, due 2048
Debt Instrument [Line Items]
Debt amount	$ 575			575
Interest rate, stated percentage	2.75%
Recourse Debt \| Senior Secured First Lien Notes, due 2024
Debt Instrument [Line Items]
Debt amount	$ 600			0
Interest rate, stated percentage	3.75%	3.75%
Recourse Debt \| Senior Secured First Lien Notes, due 2029
Debt Instrument [Line Items]
Debt amount	$ 500			0
Interest rate, stated percentage	4.45%	4.45%
Recourse Debt \| Term loan facility
Debt Instrument [Line Items]
Debt amount	$ 0			1,698
Recourse Debt \| Term loan facility \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	1.75%
Recourse Debt \| Tax-exempt bonds
Debt Instrument [Line Items]
Debt amount	$ 466			466
Recourse Debt \| Tax-exempt bonds \| Minimum
Debt Instrument [Line Items]
Interest rate, stated percentage	4.125%
Recourse Debt \| Tax-exempt bonds \| Maximum
Debt Instrument [Line Items]
Interest rate, stated percentage	6.00%
Non Recourse Debt
Debt Instrument [Line Items]
Debt amount	$ 117			168
Non Recourse Debt \| Agua Caliente Borrower 1, due 2038
Debt Instrument [Line Items]
Debt amount	$ 83			86
Interest rate, stated percentage	5.43%
Non Recourse Debt \| Midwest Generation
Debt Instrument [Line Items]
Debt amount	$ 0			48
Interest rate, stated percentage	4.39%
Non Recourse Debt \| Other
Debt Instrument [Line Items]
Debt amount	$ 34			$ 34