Earnings per Share - Earnings per share reconciliation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Schedule of Basic And Diluted Earnings [Line Items]
Adjusted Net Income Available to Common Shareholders, Common	$ (54)	$ (1,032)	$ (105)	$ (1,342)
Preferred Stock Dividends and Other Adjustments	3	3	5	5
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	$ (51)	$ (1,029)	$ (100)	$ (1,337)
Weighted Average Number of Shares Outstanding, Basic	209,129	208,496	210,261	208,207
Income (Loss) from Continuing Operations, Per Basic Share	$ (0.25)	$ (4.94)	$ (0.50)	$ (6.44)
Earnings Per Share, Basic	$ (0.25)	$ (4.94)	$ (0.50)	$ (6.44)
Weighted Average Number of Shares Outstanding, Diluted	209,129	208,496	210,261	208,207
Income (Loss) from Continuing Operations, Per Diluted Share	$ (0.25)	$ (4.94)	$ (0.50)	$ (6.44)
Earnings Per Share, Diluted	$ (0.25)	$ (4.94)	$ (0.50)	$ (6.44)
Stock Options [Member]
Schedule of Basic And Diluted Earnings [Line Items]
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	0	0	0	0
Restricted Stock and Performance Shares [Member]
Schedule of Basic And Diluted Earnings [Line Items]
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	0	0	0	0