Note 5 - Investments Schedule of Contractual Maturities (Details) - USD ($) $ in Thousands		Mar. 31, 2017	Dec. 31, 2016
Available-for-sale Securities, Amortized Cost
Available-for-sale Debt Securities, Amortized Cost Basis		$ 2,941,528	$ 2,856,468
Available-for-sale Securities, Fair Value
Available-for-sale Securities, Debt Securities		2,937,415	2,838,512
Debt Securities
Available-for-sale Securities, Amortized Cost
Available-for-sale Debt Securities, Amortized Cost Basis		2,941,528
Available-for-sale Securities, Fair Value
Available-for-sale Securities, Debt Securities		2,937,415
Non Asset Backed Security Investments, Contractual Maturities
Available-for-sale Securities, Amortized Cost
Due in one year or less	[1]	65,472
Due after one year through five years	[1]	411,562
Due after five years through ten years	[1]	905,821
Due after ten years	[1]	399,864
Available-for-sale Securities, Fair Value
Due in one year or less	[1]	65,502
Due after one year through five years	[1]	414,006
Due after five years through ten years	[1]	901,736
Due after ten years	[1]	401,998
RMBS
Available-for-sale Securities, Amortized Cost
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Amortized Cost Basis	[2]	278,710
Available-for-sale Securities, Fair Value
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value	[2]	273,549
CMBS
Available-for-sale Securities, Amortized Cost
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Amortized Cost Basis	[2]	402,848
Available-for-sale Securities, Fair Value
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value	[2]	402,525
Other ABS
Available-for-sale Securities, Amortized Cost
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Amortized Cost Basis	[2]	477,251
Available-for-sale Securities, Fair Value
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value	[2]	478,099
2013 Freddie Mac Agreement [Member] | Radian Guaranty Inc [Member]
Available-for-sale Securities, Fair Value
Marketable Securities, Restricted		$ 64,300	$ 63,900

[1] Actual maturities may differ as a result of calls before scheduled maturity.

[2] RMBS, CMBS and Other ABS are shown separately, as they are not due at a single maturity date.