Note 1 - Organization and Summary of Significant Accounting Policies - Effect of Error Correction on Financial Statements (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net income (loss)	$ 39	$ 45	$ (173)	$ 38	$ 86	$ 112	$ (66)	$ 101	$ (51)	$ 233	$ 440
Less: Noncontrolling interests net income				2					10	13	13
Less: Redeemable noncontrolling interests net loss				(22)					(30)	(6)
Net income (loss) attributable to the parent company	$ 40	$ 45	$ (174)	$ 58	$ 85	$ 111	$ (68)	$ 98	$ (31)	$ 226	$ 427
Basic (in dollars per share)	$ 0.28	$ 0.31	$ (1.20)	$ 0.40	$ 0.59	$ 0.77	$ (0.47)	$ 0.68	$ (0.21)	$ 1.57	$ 2.94
Diluted (in dollars per share)	$ 0.27	$ 0.31	$ (1.20)	$ 0.40	$ 0.58	$ 0.77	$ (0.47)	$ 0.68	$ (0.21)	$ 1.56	$ 2.91
Total comprehensive loss				$ (84)					$ (80)	$ 609	$ 410
Less: Comprehensive loss attributable to noncontrolling interests				17					(27)	(9)	(7)
Less: Comprehensive (income) loss attributable to redeemable noncontrolling interests				14					36	1	6
Comprehensive income (loss) attributable to the parent company				(53)					(71)	601	$ 409
Redeemable noncontrolling interests	$ 180			155	$ 167				180	167
Retained earnings	$ 530			664	$ 622				$ 530	$ 622
Previously Reported [Member]
Net income (loss)				38
Less: Noncontrolling interests net income				2
Less: Redeemable noncontrolling interests net loss				(2)
Net income (loss) attributable to the parent company				$ 38
Basic (in dollars per share)				$ 0.26
Diluted (in dollars per share)				$ 0.26
Total comprehensive loss				$ (84)
Less: Comprehensive loss attributable to noncontrolling interests				17
Less: Comprehensive (income) loss attributable to redeemable noncontrolling interests				(6)
Comprehensive income (loss) attributable to the parent company				(73)
Redeemable noncontrolling interests				175
Retained earnings				644
Revision of Prior Period, Adjustment [Member]
Net income (loss)				0
Less: Noncontrolling interests net income
Less: Redeemable noncontrolling interests net loss				(20)
Net income (loss) attributable to the parent company				$ 20
Basic (in dollars per share)				$ 0.14
Diluted (in dollars per share)				$ 0.14
Total comprehensive loss				$ 0
Less: Comprehensive loss attributable to noncontrolling interests
Less: Comprehensive (income) loss attributable to redeemable noncontrolling interests				20
Comprehensive income (loss) attributable to the parent company				20
Redeemable noncontrolling interests				(20)
Retained earnings				$ 20