Derivatives - Interest-Rate Derivatives (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Derivative [Line Items]
Debt referenced to LIBOR	$ 38,494	$ 38,494	$ 38,588
LIBOR
Derivative [Line Items]
Debt referenced to LIBOR	1,500	1,500
Interest Rate Swap, 6.835%
Derivative [Line Items]
Notional Principal Amount	$ 400	$ 400
Weighted-Average Interest Rate	6.348%	6.348%
Interest Rate Swap, 6.891%
Derivative [Line Items]
Notional Principal Amount	$ 350	$ 350
Weighted-Average Interest Rate	6.662%	6.662%
Interest Rate Swap, 6.570%
Derivative [Line Items]
Notional Principal Amount	$ 275	$ 275
Weighted-Average Interest Rate	6.709%	6.709%
Interest Rate Swap, 6.445%
Derivative [Line Items]
Notional Principal Amount	$ 450	$ 450
Weighted-Average Interest Rate	6.445%	6.445%
Interest Rate Swaps
Derivative [Line Items]
Net cash receipts (payments) related to settlements	$ 3	$ (47)
Collateral paid with respect to interest rate swap agreements	$ 221	$ 320

Derivative Instrument, Collateral Paid

No definition available.

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- Definition

Average fixed interest rate related to the group of interest rate derivatives.

+ References

No definition available.

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- Definition

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.

+ References

No definition available.

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- Definition

Nominal or face amount used to calculate payment on derivative.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
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- Definition

The net cash outflow or inflow from derivative instruments during the period, which are classified as financing activities, excluding those designated as hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
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