Note 3 - Segment Reporting Adjusted Pretax Operating Income (Loss) (Details) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) $ / shares		Sep. 30, 2018 USD ($)
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Adjusted pretax operating income (loss)	$ 212,743	$ 196,699	$ 630,652		$ 551,811
Net gains (losses) on investments and other financial instruments	13,009	(4,480)	47,462		(30,771)
Loss on extinguishment of debt	(5,940)	0	(22,738)		0
Amortization and impairment of other acquired intangible assets	(2,139)	(3,472)	(6,465)		(8,968)
Impairment of other long-lived assets and other-non-operating items	0	(4,059)	(5,557)		(4,371)
Consolidated pretax income (loss)	$ 217,673	184,688	643,354		507,701
Increase in Net Premium Earned			32,900
Reduction in Other Operating Expense			$ 6,200
Percent of LTV at which HPA Must Be Canceled Automatically	0.78		0.78
Mortgage Insurance Segment
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Adjusted pretax operating income (loss)	$ 214,256	204,620	$ 641,791	[1]	573,771
Increase in Net Premiums Earned Per Share | $ / shares			$ 0.12
Decrease in Other Operating Expenses Per Share | $ / shares			$ 0.02
Mortgage and Real Estate Services Segment
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Adjusted pretax operating income (loss)	$ (1,513)	$ (7,921)	$ (11,139)		$ (21,960)

[1] Includes a cumulative adjustment to unearned premiums recorded in the second quarter of 2019 related to an update to the amortization rates used to recognize revenue for Single Premium Policies, as further described below.