Consolidated Statements of Changes in Equity - USD ($) $ in Millions		Total	Member's Equity	Accumulated Other Comprehensive Income (Loss)
Balance at Dec. 31, 2017		$ 43,009	$ 42,778	$ 231
Cash distributions		(1,100)	(1,100)
Comprehensive income (loss), net of tax		1,146	1,145	1
Balance at Mar. 31, 2018		43,052	42,795	257
Balance at Dec. 31, 2017		43,009	42,778	231
Cash distributions		(2,275)		0
Comprehensive income (loss), net of tax		2,455
Balance at Jun. 30, 2018		43,186	42,929	257
Balance at Mar. 31, 2018		43,052	42,795	257
Cash distributions		(1,175)	(1,175)	0
Comprehensive income (loss), net of tax		1,309	1,309	0
Balance at Jun. 30, 2018		43,186	42,929	257
Cumulative Effect of New Accounting Principle in Period of Adoption | Difference between Revenue Guidance in Effect before and after Topic 606	[1]	(3)	(3)	0
Cumulative Effect of New Accounting Principle in Period of Adoption | Accounting Standards Update 2016-01	[2]	0	1	(1)
Cumulative Effect of New Accounting Principle in Period of Adoption | Accounting Standards Update 2018-02	[3]	0	(26)	26
Balance at Dec. 31, 2018		42,649	42,519	130
Cash distributions		(1,200)	(1,200)
Comprehensive income (loss), net of tax		1,315	1,253	62
Balance at Mar. 31, 2019		42,764	42,572	192
Balance at Dec. 31, 2018		42,649	42,519	130
Cash distributions		(2,400)		0
Comprehensive income (loss), net of tax		2,653
Balance at Jun. 30, 2019		42,902	42,710	192
Balance at Mar. 31, 2019		42,764	42,572	192
Cash distributions		(1,200)	(1,200)	0
Comprehensive income (loss), net of tax		1,338	1,338	0
Balance at Jun. 30, 2019		$ 42,902	$ 42,710	$ 192

[1] Accounting Standards Codification Topic 606 - Revenue from Contracts with Customers

[2] Accounting Standards Update (ASU) No. 2016-01 Financial Instruments - Recognition and Measurement of Financial Assets and Financial Liabilities

[3] No. 2018-02 Income Statement - Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income