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, 2016	$ 17,386	$ 144	$ 7,884	$ 10,101	$ (896)	$ 153
Net (Loss) Income Including Noncontrolling Interests	1,034			1,077		(43)
Other comprehensive income (loss), net of tax	52				52
Compensation—restricted stock units	(10)		(8)	(2)
Stock Issued During Period, Value, New Issues	402	3	321	78
Dividends Paid	(500)			(500)
Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect	0			182	(182)
Other	(9)	1	0	0		(10)
Net change	969	4	313	835	(130)	(53)
Ending 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