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)	$ 96
Increase (Decrease) in Stockholders' Equity
Issuance of common stock through dividend reinvestment, incentive and benefit plans		10
Shares withheld to satisfy tax withholdings			(29)
Share-based compensation and other, net			77
Dividends declared			(558)
Other comprehensive income (loss)	$ 42			42
Net income (loss)	(5,794)				(5,794)
Other					1
Balance at end of period at Jun. 30, 2019	$ 13,673	1,090	22,342	(2,419)	(7,340)
Increase (Decrease) in Stockholders' Equity
DIVIDENDS DECLARED PER COMMON SHARE (in dollars per share)	$ 0.50
Balance at beginning of period at Mar. 31, 2019		1,090	22,575	(2,429)	(7,712)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock through dividend reinvestment, incentive and benefit plans		0
Shares withheld to satisfy tax withholdings			(3)
Share-based compensation and other, net			44
Dividends declared			(274)
Other comprehensive income (loss)	$ 10			10
Net income (loss)	371				371
Other					1
Balance at end of period at Jun. 30, 2019	$ 13,673	1,090	22,342	(2,419)	(7,340)
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			(35)
Share-based compensation and other, net			99
Dividends declared			(562)
Other comprehensive income (loss)	(222)			(222)
Net income (loss)	691				691
Other					5
Balance at end of period at Jun. 30, 2020	$ 13,462	1,097	21,376	(2,902)	(6,109)
Increase (Decrease) in Stockholders' Equity
DIVIDENDS DECLARED PER COMMON SHARE (in dollars per share)	$ 0.50
Balance at beginning of period at Mar. 31, 2020		1,098	21,634	(2,955)	(6,486)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock through dividend reinvestment, incentive and benefit plans		(1)
Shares withheld to satisfy tax withholdings			(2)
Share-based compensation and other, net			20
Dividends declared			(276)
Other comprehensive income (loss)	$ 53			53
Net income (loss)	377				377
Other					0
Balance at end of period at Jun. 30, 2020	$ 13,462	$ 1,097	$ 21,376	$ (2,902)	$ (6,109)
Increase (Decrease) in Stockholders' Equity
DIVIDENDS DECLARED PER COMMON SHARE (in dollars per share)	$ 0.25