Note 3 - Segment Reporting Adjusted Pretax Operating Income (Loss) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2019		Jun. 30, 2018	Jun. 30, 2019		Jun. 30, 2018
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Adjusted pretax operating income (loss)	$ 215,839		$ 191,009	$ 417,909		$ 355,112
Net gains (losses) on investments and other financial instruments	12,540		(7,404)	34,453		(26,291)
Loss on extinguishment of debt	(16,798)		0	(16,798)		0
Amortization and impairment of other acquired intangible assets	(2,139)		(2,748)	(4,326)		(5,496)
Impairment of other long-lived assets and other-non-operating items	103		(286)	(5,557)		(312)
Consolidated pretax income (loss)	$ 209,545		180,571	425,681		323,013
Mortgage Insurance Segment
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Decrease in Other Operating Expenses Per Share	$ 0.02
Increase in Net Premiums Earned Per Share	$ 0.12
Adjusted pretax operating income (loss)	$ 219,365	[1]	197,440	427,535	[1]	369,151
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)	$ (3,526)		$ (6,431)	$ (9,626)		$ (14,039)

[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.