Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Millions	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests
Balance, beginning at Dec. 31, 2018	$ 16,580	$ 132	$ 8,176	$ 9,524	$ (1,324)	$ 72
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(1,001)			(989)		(12)
Other comprehensive income (loss), net of tax	501				501
Compensation—restricted stock units	(3)		0	(3)
Other	23		20	5	0	(2)
Net change	(480)		20	(987)	501	(14)
Balance, ending at Sep. 30, 2019	16,100	132	8,196	8,537	(823)	58
Balance, beginning at Jun. 30, 2019	17,329	132	8,157	9,910	(933)	63
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(1,376)			(1,372)		(4)
Other comprehensive income (loss), net of tax	110				110
APIC, Share-based Payment Arrangement, Restricted Stock Unit, Increase for Cost Recognition			19	(1)
Compensation—restricted stock units	18
Other	19		20	0		(1)
Net change	(1,229)		39	(1,373)	110	(5)
Balance, ending at Sep. 30, 2019	16,100	132	8,196	8,537	(823)	58
Balance, beginning at Dec. 31, 2019	16,367	132	8,222	8,788	(862)	87
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(175)			(163)		(12)
Other comprehensive income (loss), net of tax	876				876
APIC, Share-based Payment Arrangement, Restricted Stock Unit, Increase for Cost Recognition			1	(4)
Compensation—restricted stock units	(3)
Other	23	0	0	3	0	20
Net change	574		1	(311)	876	8
Balance, ending at Sep. 30, 2020	16,941	132	8,223	8,477	14	95
Balance, beginning at Jun. 30, 2020	16,737	132	8,204	8,356	(34)	79
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	117			121		(4)
Other comprehensive income (loss), net of tax	48				48
Compensation—restricted stock units	19		19	0
Other	20		0	0		20
Net change	204		19	121	48	16
Balance, ending at Sep. 30, 2020	$ 16,941	$ 132	$ 8,223	$ 8,477	$ 14	$ 95