CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Millions	Total	COMMON STOCK	ADDITIONAL PAID-IN CAPITAL	ACCUMULATED OTHER COMPREHENSIVE LOSS	ACCUMULATED DEFICIT	ACCUMULATED DEFICIT Cumulative Effect, Period of Adoption, Adjustment
Balance at beginning of period at Dec. 31, 2018		$ 1,080	$ 22,852	$ (2,461)	$ (1,643)	$ 115
Increase (Decrease) in Stockholders' Equity
Issuance of common stock through dividend reinvestment, incentive and benefit plans		10
Shares withheld to satisfy tax withholdings			(35)
Share-based compensation and other, net			115
Dividends declared			(831)
Other comprehensive income (loss)	$ (38)			(38)
Net income (loss)	(5,492)				(5,492)
Other					2
Balance at end of period at Sep. 30, 2019	$ 13,674	1,090	22,101	(2,499)	(7,018)
Increase (Decrease) in Stockholders' Equity
DIVIDENDS DECLARED PER COMMON SHARE (in dollars per share)	$ 0.75
Balance at beginning of period at Jun. 30, 2019		1,090	22,342	(2,419)	(7,321)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock through dividend reinvestment, incentive and benefit plans		0
Shares withheld to satisfy tax withholdings			(6)
Share-based compensation and other, net			38
Dividends declared			(273)
Other comprehensive income (loss)	$ (80)			(80)
Net income (loss)	302				302
Other					1
Balance at end of period at Sep. 30, 2019	$ 13,674	1,090	22,101	(2,499)	(7,018)
Increase (Decrease) in Stockholders' Equity
DIVIDENDS DECLARED PER COMMON SHARE (in dollars per share)	$ 0.25
Balance at beginning of period at Dec. 31, 2019	$ 13,470	1,090	21,874	(2,680)	(6,814)	$ 9
Increase (Decrease) in Stockholders' Equity
Issuance of common stock through dividend reinvestment, incentive and benefit plans		7
Shares withheld to satisfy tax withholdings			(39)
Share-based compensation and other, net			132
Dividends declared			(837)
Other comprehensive income (loss)	(115)			(115)
Net income (loss)	1,057				1,057
Other					5
Balance at end of period at Sep. 30, 2020	$ 13,689	1,097	21,130	(2,795)	(5,743)
Increase (Decrease) in Stockholders' Equity
DIVIDENDS DECLARED PER COMMON SHARE (in dollars per share)	$ 0.75
Balance at beginning of period at Jun. 30, 2020		1,097	21,376	(2,902)	(6,109)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock through dividend reinvestment, incentive and benefit plans		0
Shares withheld to satisfy tax withholdings			(4)
Share-based compensation and other, net			33
Dividends declared			(275)
Other comprehensive income (loss)	$ 107			107
Net income (loss)	366				366
Other					0
Balance at end of period at Sep. 30, 2020	$ 13,689	$ 1,097	$ 21,130	$ (2,795)	$ (5,743)
Increase (Decrease) in Stockholders' Equity
DIVIDENDS DECLARED PER COMMON SHARE (in dollars per share)	$ 0.25