Note 6 - (Loss) Earnings Per Common Share - Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended			6 Months Ended
		Jun. 30, 2021		Jun. 30, 2020	Jun. 30, 2021		Jun. 30, 2020
Net income (loss)		$ 449		$ (71)	$ 1,048		$ (167)
Less: Series A convertible preferred stock dividend				25	24		49
Less: Excess consideration paid for redemption of preferred shares		803	[1]		803	[1]
Net (loss) income available to common stockholders – basic		(354)		(96)	221		(216)
Net (loss) income available to common stockholders – diluted		$ (354)		$ (96)	$ 221		$ (216)
Weighted-average common shares outstanding – basic (in shares)		844		759	805		760
Effect of dilutive securities:
Effect of dilutive securities (in shares)					17
Weighted-average common shares outstanding – diluted (in shares)		844		759	822		760
Basic (Note 6) (in dollars per share)		$ (0.42)		$ (0.13)	$ 0.27		$ (0.28)
Diluted (Note 6) (in dollars per share)		$ (0.42)		$ (0.13)	$ 0.27		$ (0.28)
Total (in shares)		33		153	63		153
Share-based Payment Arrangement [Member]
Effect of dilutive securities:
Total (in shares)		24		38	1		38
Series A Convertible Preferred Stock [Member]
Effect of dilutive securities:
Effect of dilutive securities (in shares)	[2]	9		115	62		115

[1] Refer to Note 6 ((Loss) Earnings per Share) and Note 14 (Shareholders' Equity) to the consolidated financial statements for additional information.

[2] For the three and six months ended June 30, 2021 and 2020, the Preferred Stock was anti-dilutive; therefore, it was excluded from the calculation of diluted (loss) earnings per share.