Earnings Per Share - Reconciliation of Information Used to Compute Basic and Diluted EPS (Details) - USD ($) shares in Millions, $ in Millions		3 Months Ended		6 Months Ended	9 Months Ended		12 Months Ended
	Oct. 15, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Income (loss) from continuing operations attributable to common shareholders		$ 36	$ 58		$ 105	$ 8
Income from discontinued operations after income taxes (B)		0	37		50	153
Net income (loss)		36	95		155	161
Less: preferred stock dividends declared		(1)	(1)		(2)	(2)
Net income available to the Company's common shareholders - basic		35	94		153	159
Add: Interest expense related to convertible notes		0	3		0	0
Net income available to the Company's common shareholders - diluted		$ 35	$ 97		$ 153	$ 159
Average shares outstanding - basic (in shares)		436	436		436	451
Effect of dilutive securities:
Stock options (in shares)		0	1		0	1
Stock and performance awards (in shares)		3	5		4	3
Convertible notes (in shares)		0	15		0	0
Average shares outstanding - diluted (in shares)		439	457		440	455
Common stock outstanding (in shares)		434	434		434	434	434
Decrease in average shares outstanding (in shares)							15
Incremental common shares attributable to dilutive effect of accelerated share repurchase agreements (in shares)				55
Convertible notes
Effect of dilutive securities:
Number of shares of common stock previously attributable to the convertible notes (in shares)	15	0	0		0	15