Consolidated Statements of Changes in Equity - USD ($) $ in Millions	Total	Members Equity	Accumulated Other Comprehensive Income (Loss) [Member]
Balance at Dec. 31, 2014	$ 34,734	$ 34,736	$ (2)
Increase (Decrease) in Total Equity [Roll Forward]
Comprehensive income, net of tax	4,298	4,248	50
Cash distributions to Parent	(4,000)	(4,000)	0
Balance at Dec. 31, 2015	35,032	34,984	48
Increase (Decrease) in Total Equity [Roll Forward]
Comprehensive income, net of tax	3,640	3,569	71
Cash distributions to Parent	(2,500)	(2,500)	0
Balance at Dec. 31, 2016	36,172	36,053	119
Increase (Decrease) in Total Equity [Roll Forward]
Comprehensive income, net of tax	11,412	11,300	112
Cash distributions to Parent	(4,575)	(4,575)	0
Balance at Dec. 31, 2017	$ 43,009	$ 42,778	$ 231