CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Millions	Total	COMMON STOCK	ADDITIONAL PAID-IN CAPITAL	ACCUMULATED OTHER COMPREHENSIVE LOSS	RETAINED EARNINGS (ACCUMULATED DEFICIT)
Balance at beginning of period at Dec. 31, 2017		$ 1,069	$ 23,314	$ (1,995)	$ 1,103
Increase (Decrease) in Stockholders' Equity
Issuance of common stock through dividend reinvestment, incentive and benefit plans		10	(6)
Shares withheld to satisfy tax withholdings			(25)
Share-based compensation and other, net			33
Dividends declared			0		(586)
Other comprehensive income	$ 114			114
Net (loss) income	115				115
Balance at end of period at Mar. 31, 2018	$ 23,443	1,079	23,316	(2,288)	1,336
Increase (Decrease) in Stockholders' Equity
DIVIDENDS DECLARED PER COMMON SHARE (in dollars per share)	$ 0.54
Balance at beginning of period at Dec. 31, 2018	$ 19,828	1,080	22,852	(2,461)	(1,643)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock through dividend reinvestment, incentive and benefit plans		10	(13)
Shares withheld to satisfy tax withholdings			(26)
Share-based compensation and other, net			34
Dividends declared			(272)		0
Other comprehensive income	32			32
Net (loss) income	(6,165)				(6,165)
Balance at end of period at Mar. 31, 2019	$ 13,543	$ 1,090	$ 22,575	$ (2,429)	$ (7,693)
Increase (Decrease) in Stockholders' Equity
DIVIDENDS DECLARED PER COMMON SHARE (in dollars per share)	$ 0.25