Summarized Financial Information (Summarized Balance Sheets) (Details) - USD ($) $ in Millions		Mar. 31, 2020	Dec. 31, 2019
Condensed Financial Statements, Captions [Line Items]
Current assets		$ 3,360	$ 3,427
Current liabilities		2,165	2,282
Parent Company, Subsidiary Issuer And Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Current assets		2,469	2,464
Noncurrent assets	[1]	14,450	14,596
Current liabilities		1,413	1,472
Noncurrent liabilities	[2]	17,330	15,800
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Noncurrent assets		6,500	6,500
Noncurrent liabilities		$ 3,000	$ 1,400

[1] Includes amounts due from non-guarantor subsidiaries of $6.5 billion at both March 31, 2020 and December 31, 2019.

[2] Includes amounts due to non-guarantor subsidiaries of $3.0 billion and $1.4 billion as of March 31, 2020 and December 31, 2019