Note 5 - Investments Contractual Maturities (Details) - USD ($) $ in Thousands		Mar. 31, 2019	Dec. 31, 2018
Total Debt Securities [Line Items]
Loaned securities		$ 22,606	$ 27,860
Available-for-sale Securities, Amortized Cost
Fixed-maturity investments available for sale, Total, Amortized Cost		3,875,919	4,098,962
Available-for-sale Securities, Fair Value
Fixed-maturity investments available for sale, Total, Fair Value		3,897,584	4,021,575
Non Asset Backed Security Investments, Contractual Maturities [Member]
Available-for-sale Securities, Amortized Cost
Due in one year or less	[1]	93,413
Due after one year through five years	[1]	828,387
Due after five years through ten years	[1]	1,051,235
Due after ten years	[1]	369,044
Available-for-sale Securities, Fair Value
Due in one year or less	[1]	93,208
Due after one year through five years	[1]	832,653
Due after five years through ten years	[1]	1,060,529
Due after ten years	[1]	376,401
RMBS
Available-for-sale Securities, Amortized Cost
Fixed-maturity investments available for sale, Maturity, without Single Maturity Date, Amortized Cost	[2]	348,746
Available-for-sale Securities, Fair Value
Fixed-maturity investments available for sale, Maturity, without Single Maturity Date, Fair Value	[2]	350,238
CMBS
Available-for-sale Securities, Amortized Cost
Fixed-maturity investments available for sale, Maturity, without Single Maturity Date, Amortized Cost	[2]	512,190
Available-for-sale Securities, Fair Value
Fixed-maturity investments available for sale, Maturity, without Single Maturity Date, Fair Value	[2]	515,604
Other ABS
Available-for-sale Securities, Amortized Cost
Fixed-maturity investments available for sale, Maturity, without Single Maturity Date, Amortized Cost	[2]	679,444
Available-for-sale Securities, Fair Value
Fixed-maturity investments available for sale, Maturity, without Single Maturity Date, Fair Value	[2]	675,477
Total fixed-maturities available for sale
Available-for-sale Securities, Amortized Cost
Fixed-maturity investments available for sale, Total, Amortized Cost	[3]	3,882,459
Available-for-sale Securities, Fair Value
Fixed-maturity investments available for sale, Total, Fair Value	[3]	3,904,110
Securities Financing Transaction, Fair Value
Total Debt Securities [Line Items]
Loaned securities	[4]	22,606	27,860
Fixed maturities | Securities Financing Transaction, Fair Value
Total Debt Securities [Line Items]
Loaned securities		$ 6,500	$ 7,400

[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.

[3] Includes securities loaned under securities lending agreements with a fair value of $6.5 million.

[4] Our securities loaned under securities lending agreements are reported at fair value within other assets in our condensed consolidated balance sheets. All of our securities lending agreements are classified as overnight and revolving. None of the amounts are subject to offsetting.