Consolidated Statements of Changes in Equity - USD ($) $ in Millions	Total	Member's Equity	Accumulated Other Comprehensive Income (Loss)
Cumulative Effect of New Accounting Principle in Period of Adoption | Difference between Revenue Guidance in Effect before and after Topic 606 [Member]	$ (3)	$ (3)	$ 0
Cumulative Effect of New Accounting Principle in Period of Adoption | Accounting Standards Update 2016-01 [Member]	0	1	(1)
Cumulative Effect of New Accounting Principle in Period of Adoption | Accounting Standards Update 2018-02 [Member]	0	(26)	26
Balance at Dec. 31, 2017	43,009	42,778	231
Cash distributions	(4,150)	(4,150)	0
Comprehensive income (loss), net of tax	3,847	3,847	0
Balance at Sep. 30, 2018	$ 42,703	$ 42,447	$ 256