Consolidated Statements of Changes in Stockholder's Equity - USD ($) $ in Millions	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests
Beginning balance at Dec. 31, 2017	$ 18,355	$ 148	$ 8,197	$ 10,936	$ (1,026)	$ 100
Net (Loss) Income Including Noncontrolling Interests	1,049			1,073		(24)
Other comprehensive income (loss), net of tax	(319)				(319)
Compensation—restricted stock units	(5)		0	(5)
sharerepurchase	(2,496)	(16)		(2,480)
Other	(4)	0	(21)	0	21	(4)
Net change	(1,775)	(16)	(21)	(1,412)	(298)	(28)
Ending balance at Dec. 31, 2018	16,580	132	8,176	9,524	(1,324)	72
Net (Loss) Income Including Noncontrolling Interests	(751)			(734)		(17)
Other comprehensive income (loss), net of tax	462				462
Compensation—restricted stock units	19		26	(7)
Other	57	0	20	5	0	32
Net change	(213)	0	46	(736)	462	15
Ending balance at Dec. 31, 2019	16,367	132	8,222	8,788	(862)	87
Net (Loss) Income Including Noncontrolling Interests	150			166		(16)
Other comprehensive income (loss), net of tax	875				875
Compensation—restricted stock units	11		20	(9)
Other	23	0	0	4	0	19
Net change	912	0	20	14	875	3
Ending balance at Dec. 31, 2020	17,279	$ 132	$ 8,242	8,802	$ 13	$ 90
Cumulative Effect of New Accounting Principle in Period of Adoption	$ (147)			$ (147)