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	143					143			0
Other comprehensive income (J)	258							258	0
Cash dividends declared:
Preferred dividends declared, value		$ (1)					$ (1)
Common share, value	(58)					(58)
Stock-based compensation	15				15
Common stock issued: compensation plans	1			2	(1)
Balance at end of period at Mar. 31, 2018	5,282		55	483	8,280	(1,164)		(2,386)	14
Balance at beginning of period at Dec. 31, 2017	4,924		55	481	8,266	(1,248)		(2,644)	14
Cash dividends declared:
Other	1					1
Balance at end 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	187					187			0
Other comprehensive income (J)	76							76	0
Cash dividends declared:
Preferred dividends declared, value		$ (1)					$ (1)
Common share, value	(38)					(38)
Repurchase and retirement of common stock (H)	(700)			(32)	(668)
Stock-based compensation	8				8
Common stock issued: compensation plans	(13)			2	(15)
Balance at end of period at Mar. 31, 2019	$ 5,178		$ 55	$ 453	$ 7,644	$ (134)		$ (2,852)	$ 12