Note 10 - Earnings Per Share - Reconciliation of the Numerators and Denominators of the Earnings per Share Calculations (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net income (loss) available to common stockholders - Numerator basic and diluted	$ (31)	$ 226	$ 427
Weighted-average common shares outstanding - Basic (in shares)	144.5	144.0	145.0
Employee compensation-related shares, including stock options (in shares)	0.0	1.1	1.5
Weighted-average common shares outstanding - Diluted (in shares)	144.5	145.1	146.5