Debt 1 (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Total Long-term Debt	$ 20,447	$ 24,153
Year-End Stated Rate on Debt	2.68%	1.51%
Unamortized Underwriting Fees	$ (30)	$ (49)
Long Term Debt [Member]
Debt Instrument [Line Items]
Year-End Stated Rate on Debt	2.47%	2.21%
Fixed Rate Senior Notes Amount [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date Range, Start	2019
Debt Instrument, Maturity Date Range, End	2027
Total Long-term Debt	$ 16,677	$ 19,652
Year-End Stated Rate on Debt	2.28%	2.24%
Year End Interest Rate With Swaps	3.06%	2.27%
Floating Rate Senior Notes Amount [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date Range, Start	2019
Debt Instrument, Maturity Date Range, End	2022
Total Long-term Debt	$ 3,800	$ 4,550
Year-End Stated Rate on Debt	3.31%	2.09%
Year End Interest Rate With Swaps	0.00%	0.00%

Latest date the outstanding debt instruments are required to be repaid.

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- Definition

Earliest date the outstanding debt instruments are required to be repaid.

+ References

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- Definition

Reflects as of the balance-sheet date the effective interest rates on debt outstanding presented if swaps are in place to hedge the underlying debt.

+ References

No definition available.

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- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
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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.

+ References

No definition available.

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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
-SubTopic 20
-Section 50
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- Definition

The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

+ References

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