Note 5 - Investments Unrealized Gain (Loss) on Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2017		Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost Debt and Equity Securities	$ 3,440,462		$ 2,857,798
Available-for-sale Securities	3,478,709		2,839,842
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	49,063		20,827
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	10,816		38,783
US government and agency securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost Debt and Equity Securities	61,287		78,931
Available-for-sale Securities	60,860		75,474
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	187		2
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	614		3,459
US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost Debt and Equity Securities	125,485		66,124
Available-for-sale Securities	129,507		67,171
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	4,461		1,868
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	439		821
Corporate bonds and notes
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost Debt and Equity Securities	1,806,796		1,463,720
Available-for-sale Securities	1,836,316		1,455,628
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	34,927		14,320
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	5,407		22,412
RMBS
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost Debt and Equity Securities	176,789		358,262
Available-for-sale Securities	175,408		350,628
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	796		197
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	2,177		7,831
CMBS
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost Debt and Equity Securities	433,916		429,057
Available-for-sale Securities	436,892		428,289
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	4,167		2,255
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	1,191		3,023
Other ABS
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost Debt and Equity Securities	616,687		433,603
Available-for-sale Securities	618,832		434,728
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	2,627		2,037
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	482		912
Foreign government securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost Debt and Equity Securities	31,437		24,771
Available-for-sale Securities	32,392		24,594
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	961		148
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	6		325
Other than Securities Investment [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost Debt and Equity Securities			2,000
Available-for-sale Securities			2,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax			0
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax			0
Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost Debt and Equity Securities	3,252,397	[1]	2,856,468
Available-for-sale Securities	3,290,207	[1]	2,838,512
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	48,126	[1]	20,827
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	10,316	[1]	38,783
Equity securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost Debt and Equity Securities	188,065	[1],[2]	1,330	[3]
Available-for-sale Securities	188,502	[1],[2]	1,330	[3]
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	937	[1],[2]	0	[3]
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	$ 500	[1],[2]	$ 0	[3]

[1] Includes loaned securities under securities lending agreements that are classified as other assets in our condensed consolidated balance sheets, as further described below.

[2] Primarily consists of investments in fixed income and equity exchange-traded funds and publicly-traded business development company equities.

[3] Primarily consists of investments in Federal Home Loan Bank stock as required in connection with the memberships of Radian Guaranty and Radian Reinsurance in the FHLB.