CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Millions	Total controlling interest shareholders' equity	Shares	Additional paid-in capital	Retained earnings (accumulated deficit) Period of Adoption, Adjustment	Retained earnings (accumulated deficit)	Accumulated other comprehensive loss Period of Adoption, Adjustment	Accumulated other comprehensive loss	Noncontrolling interest	Total
Balance at Dec. 31, 2018	$ 13,107	$ 59	$ 13,394		$ (67)		$ (279)	$ 7	$ 13,114
Increase (Decrease) in Shareholders' Equity
Share-based compensation	28		28						28
Net income (loss) attributable to controlling interest					(1,204)				(1,204)
Other comprehensive income (loss) attributable to controlling interest							8		8
Total comprehensive income (loss) attributable to controlling interest	(1,196)								(1,196)
Total comprehensive income attributable to noncontrolling interest								2
Total comprehensive income (loss)									(1,194)
Other, net	(6)		(7)						(6)
Balance at Sep. 30, 2019	11,933	59	13,415	$ 25	(1,246)	$ (24)	(295)	9	11,942
Balance at Jun. 30, 2019	12,748	59	13,405		(421)		(295)	9	12,757
Increase (Decrease) in Shareholders' Equity
Share-based compensation	9		9						9
Net income (loss) attributable to controlling interest					(825)				(825)
Total comprehensive income (loss) attributable to controlling interest	(825)								(825)
Total comprehensive income (loss)									(825)
Other, net	1		1						1
Balance at Sep. 30, 2019	11,933	59	13,415	25	(1,246)	$ (24)	(295)	9	11,942
Balance at Dec. 31, 2019	11,862	59	13,424		(1,297)		(324)	5	11,867
Increase (Decrease) in Shareholders' Equity
Issuance of shares under share-based compensation plans		1
Share-based compensation	24		24						24
Equity component of convertible debt instruments	46		46						46
Net income (loss) attributable to controlling interest					(530)				(530)
Other comprehensive income (loss) attributable to controlling interest							(3)		(3)
Total comprehensive income (loss) attributable to controlling interest	(533)								(533)
Total comprehensive income attributable to noncontrolling interest								1
Total comprehensive income (loss)									(532)
Other, net	(2)		(1)						(2)
Balance at Sep. 30, 2020	11,397	60	13,493	(2)	(1,829)		(327)	6	11,403
Balance at Jun. 30, 2020	10,981	60	13,438		(2,188)		(329)	6	10,987
Increase (Decrease) in Shareholders' Equity
Share-based compensation	9		9						9
Equity component of convertible debt instruments	46		46						46
Net income (loss) attributable to controlling interest					359				359
Other comprehensive income (loss) attributable to controlling interest							2		2
Total comprehensive income (loss) attributable to controlling interest	361								361
Total comprehensive income (loss)									361
Balance at Sep. 30, 2020	$ 11,397	$ 60	$ 13,493	$ (2)	$ (1,829)		$ (327)	$ 6	$ 11,403