Condensed Consolidated Statement of Equity - USD ($) shares in Millions, $ in Millions		Total	Common Stock [Member]	6.875% Mandatory Convertible Preferred Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Foreign Currency Adjustment Attributable to Parent [Member]	Dividends/Distributions in Excess of Earnings [Member]
Balance, shares Period Start at Dec. 31, 2017			406
Balance, value Period Start at Dec. 31, 2017		$ 12,339	$ 4	$ 0	$ 16,844	$ (4)	$ (4,505)
Preferred Stock, Shares Outstanding Period Start at Dec. 31, 2017				2
Stock-based compensation related activity, net of forfeitures, value		92			92
Stock-based compensation related activity, net of forfeitures, shares			1
Purchases and retirement of common stock, value		(34)			(34)
Stock Issued During Period, Shares, New Issues			8
Stock Issued During Period, Value, New Issues		841			841
Common stock dividends/distributions	[1]	(1,315)					(1,315)
Dividends/distributions on preferred stock	[1]	(85)					(85)
Foreign currency translation adjustments	[2]	(1)				(1)
Net income (loss)		458					458
Balance, shares Period End at Sep. 30, 2018			415
Balance, value Period End at Sep. 30, 2018		12,295	$ 4	$ 0	17,743	(5)	(5,447)
Preferred Stock, Shares Outstanding Period End at Sep. 30, 2018				2
Balance, shares Period Start at Jun. 30, 2018			415
Balance, value Period Start at Jun. 30, 2018		12,566	$ 4	$ 0	17,711	(5)	(5,144)
Preferred Stock, Shares Outstanding Period Start at Jun. 30, 2018				2
Stock-based compensation related activity, net of forfeitures, value		32			32
Stock-based compensation related activity, net of forfeitures, shares			0
Purchases and retirement of common stock, value		(1)			(1)
Stock Issued During Period, Shares, New Issues			0
Stock Issued During Period, Value, New Issues		1			1
Purchases and retirement of common stock, shares			0
Common stock dividends/distributions	[1]	(439)					(439)
Dividends/distributions on preferred stock	[1]	(28)					(28)
Foreign currency translation adjustments		0				0
Net income (loss)		164					164
Balance, shares Period End at Sep. 30, 2018			415
Balance, value Period End at Sep. 30, 2018		$ 12,295	$ 4	$ 0	17,743	(5)	(5,447)
Preferred Stock, Shares Outstanding Period End at Sep. 30, 2018				2
Balance, shares Period Start at Dec. 31, 2018		415	415
Balance, value Period Start at Dec. 31, 2018		$ 12,034	$ 4	$ 0	17,767	(5)	(5,732)
Preferred Stock, Shares Outstanding Period Start at Dec. 31, 2018		2		2
Stock-based compensation related activity, net of forfeitures, value		$ 106			106
Stock-based compensation related activity, net of forfeitures, shares			1
Purchases and retirement of common stock, value		(44)			(44)
Common stock dividends/distributions	[1]	(1,415)					(1,415)
Dividends/distributions on preferred stock	[1]	(85)					(85)
Foreign currency translation adjustments		0
Net income (loss)		$ 729					729
Balance, shares Period End at Sep. 30, 2019		416	416
Balance, value Period End at Sep. 30, 2019		$ 11,325	$ 4	$ 0	17,829	(5)	(6,503)
Preferred Stock, Shares Outstanding Period End at Sep. 30, 2019		2		2
Balance, shares Period Start at Jun. 30, 2019			416
Balance, value Period Start at Jun. 30, 2019		$ 11,523	$ 4	$ 0	17,801	(5)	(6,277)
Preferred Stock, Shares Outstanding Period Start at Jun. 30, 2019				2
Stock-based compensation related activity, net of forfeitures, value		29			29
Stock-based compensation related activity, net of forfeitures, shares			0
Purchases and retirement of common stock, value		(1)			(1)
Purchases and retirement of common stock, shares			0
Common stock dividends/distributions	[1]	(470)					(470)
Dividends/distributions on preferred stock	[1]	(28)					(28)
Foreign currency translation adjustments		0
Net income (loss)		$ 272					272
Balance, shares Period End at Sep. 30, 2019		416	416
Balance, value Period End at Sep. 30, 2019		$ 11,325	$ 4	$ 0	$ 17,829	$ (5)	$ (6,503)
Preferred Stock, Shares Outstanding Period End at Sep. 30, 2019		2		2

[1] See note 7 for information regarding common and preferred stock dividends declared per share.

[2] See the condensed consolidated statement of operations and other comprehensive income (loss) for the components of other comprehensive income (loss).