Note 4 - Segment Reporting - Adjusted Pretax Operating Income (Loss) (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020 USD ($)	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2020 USD ($) segment	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Segment Reporting Information [Line Items]
Number of Reportable Segments | segment									2
Net gains (losses) on investments and other financial instruments	$ 17,376	$ 17,652	$ 47,276	$ (22,027)	$ 4,257	$ 13,009	$ 12,540	$ 21,913	$ 60,277	$ 51,719	$ (42,476)
Loss on extinguishment of debt					0	(5,940)	(16,798)	0	0	(22,738)	0
Impairment of goodwill					(4,828)	0	0	0	0	(4,828)	0
Amortization and impairment of other acquired intangible assets	$ (2,225)	$ (961)	$ (979)	$ (979)	$ (15,823)	$ (2,139)	$ (2,139)	$ (2,187)	(5,144)	(22,288)	(12,429)
Impairment of Long-Lived Assets Held-for-use									(7,759)	(7,507)	(6,404)
Consolidated pretax income									479,441	848,993	684,186
Mortgage segment
Segment Reporting Information [Line Items]
Adjusted pretax operating income (loss)									451,488	852,854	770,714
Net gains (losses) on investments and other financial instruments									0	0	0
Real Estate Segment
Segment Reporting Information [Line Items]
Adjusted pretax operating income (loss)									(23,240)	(17,987)	(4,005)
Net gains (losses) on investments and other financial instruments									0	0	0
Impairment of goodwill									0	(4,828)
Mortgage and Real Estate Services Segment
Segment Reporting Information [Line Items]
Adjusted pretax operating income (loss)									428,248	834,867	766,709
All Other activities segment
Segment Reporting Information [Line Items]
Adjusted pretax operating income (loss)									3,819	19,768	(21,214)
Net gains (losses) on investments and other financial instruments									$ 0	$ 0	$ 0