Statement of Changes in Consolidated Equity (unaudited) - USD ($) $ in Millions	Total	Preferred Class A	Preferred stock	Common stock	Additional capital	Accumulated deficit	Accumulated deficit Preferred Class A	Accumulated other comprehensive loss	Noncontrolling Interests
Balance at beginning of period at Dec. 31, 2017	$ 4,924		$ 55	$ 481	$ 8,266	$ (1,248)		$ (2,644)	$ 14
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	263					263
Other comprehensive loss (J)	88							88
Cash dividends declared:
Preferred dividends declared, value		$ (1)					$ (1)
Common share, value	(87)					(87)
Stock-based compensation	29				29
Common stock issued: compensation plans	2			2
Balance at end of period at Jun. 30, 2018	5,218		55	483	8,295	(1,073)		(2,556)	14
Balance at beginning of period at Mar. 31, 2018	5,282		55	483	8,280	(1,164)		(2,386)	14
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	120					120
Other comprehensive loss (J)	(170)							(170)
Cash dividends declared:
Common share, value	(29)					(29)
Stock-based compensation	14				14
Common stock issued: compensation plans	1				1
Balance at end of period at Jun. 30, 2018	5,218		55	483	8,295	(1,073)		(2,556)	14
Balance at beginning of period at Dec. 31, 2018	5,585		55	483	8,319	(358)		(2,926)	12
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	66					66
Other comprehensive loss (J)	59							59
Cash dividends declared:
Preferred dividends declared, value		$ (1)					$ (1)
Common share, value	(38)					(38)
Repurchase and retirement of common stock (H)	(900)			(45)	(855)
Stock-based compensation	25				25
Common stock issued: compensation plans	(3)			2	(5)
Balance at end of period at Jun. 30, 2019	4,866		55	440	7,484	(256)		(2,869)	12
Balance at beginning of period at Mar. 31, 2019	5,178		55	453	7,644	(134)		(2,852)	12
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	(121)					(121)
Other comprehensive loss (J)	(17)							(17)
Cash dividends declared:
Repurchase and retirement of common stock (H)	(200)			(13)	(187)
Stock-based compensation	17				17
Common stock issued: compensation plans	10			0	10
Other	(1)					(1)
Balance at end of period at Jun. 30, 2019	$ 4,866		$ 55	$ 440	$ 7,484	$ (256)		$ (2,869)	$ 12