Note 4 - Segment Reporting Adjusted Pretax Operating Income (Loss) (Details) $ in Thousands		3 Months Ended									12 Months Ended
		Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Jun. 30, 2017 USD ($)	Dec. 31, 2019 USD ($) segment	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Segment Reporting Information [Line Items]
Number of Reportable Segments | segment											2
Net gains (losses) on investments and other financial instruments		$ 4,257	$ 13,009	$ 12,540	$ 21,913	$ (11,705)	$ (4,480)	$ (7,404)	$ (18,887)		$ 51,719	$ (42,476)	$ 3,621
Loss on extinguishment of debt											(22,738)	0	(51,469)
Impairment of goodwill		(4,828)	0	0	0						(4,828)	0	(184,374)
Amortization and impairment of other acquired intangible assets		$ (15,823)	$ (2,139)	$ (2,139)	$ (2,187)	$ (3,461)	$ (3,472)	$ (2,748)	$ (2,748)		(22,288)	(12,429)	(27,671)
Impairment of Long-Lived Assets Held-for-use											(7,507)	(6,404)	(10,545)
Consolidated pretax income											848,993	684,186	346,737
Mortgage Insurance Segment
Segment Reporting Information [Line Items]
Adjusted pretax operating income (loss)											868,898	772,614	651,015
Net gains (losses) on investments and other financial instruments											0	0	0
Mortgage and Real Estate Services Segment
Segment Reporting Information [Line Items]
Adjusted pretax operating income (loss)	[1]										(14,263)	(27,119)	(33,840)
Net gains (losses) on investments and other financial instruments											0	0	$ 0
Impairment of goodwill										$ (184,400)	$ (4,828)	$ 0

[1] Includes inter-segment revenues as reflected in the tables below.