Note 5 - Investments Available for Sale Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	$ 4,003,367	$ 4,098,962
Debt Securities, Available-for-sale	4,113,650	4,021,575
Total fixed-maturities available for sale
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	4,026,617
Debt Securities, Available-for-sale	4,138,106
Fixed maturities \| US government and agency securities
Debt Securities, Available-for-sale [Line Items]
Available for Sale Securities, Amortized Cost	84,807	85,532
Available for Sale Securities, Fair Value	85,922	84,070
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	1,151	46
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	36	1,508
Fixed maturities \| State and municipal obligations
Debt Securities, Available-for-sale [Line Items]
Available for Sale Securities, Amortized Cost	100,214	138,022
Available for Sale Securities, Fair Value	107,962	138,313
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	7,750	2,191
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	2	1,900
Fixed maturities \| Corporate bonds and notes
Debt Securities, Available-for-sale [Line Items]
Available for Sale Securities, Amortized Cost	2,192,119	2,288,720
Available for Sale Securities, Fair Value	2,272,269	2,229,885
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	81,488	5,053
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	1,338	63,888
Fixed maturities \| RMBS
Debt Securities, Available-for-sale [Line Items]
Available for Sale Securities, Amortized Cost	425,138	334,843
Available for Sale Securities, Fair Value	433,773	332,142
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	10,060	1,785
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	1,425	4,486
Fixed maturities \| CMBS
Debt Securities, Available-for-sale [Line Items]
Available for Sale Securities, Amortized Cost	557,353	546,729
Available for Sale Securities, Fair Value	571,923	539,915
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	15,302	544
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	732	7,358
Fixed maturities \| Other ABS
Debt Securities, Available-for-sale [Line Items]
Available for Sale Securities, Amortized Cost	661,898	712,748
Available for Sale Securities, Fair Value	661,089	704,662
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	2,166	814
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	2,975	8,900
Fixed maturities \| Foreign government and agency securities
Debt Securities, Available-for-sale [Line Items]
Available for Sale Securities, Amortized Cost	5,088
Available for Sale Securities, Fair Value	5,168
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	80
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	0
Fixed maturities \| Total fixed-maturities available for sale
Debt Securities, Available-for-sale [Line Items]
Available for Sale Securities, Amortized Cost	4,026,617	4,106,594
Debt Securities, Available-for-sale, Amortized Cost	4,003,367	4,098,962
Available for Sale Securities, Fair Value	4,138,106	4,028,987
Debt Securities, Available-for-sale	4,113,650	4,021,575
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	117,997	10,433
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	6,508	88,040
Fixed maturities \| Securities Financing Transaction, Cost \| Total fixed-maturities available for sale
Debt Securities, Available-for-sale [Line Items]
Available for Sale Securities, Amortized Cost	23,250	7,632
Fixed maturities \| Securities Financing Transaction, Fair Value \| Total fixed-maturities available for sale
Debt Securities, Available-for-sale [Line Items]
Available for Sale Securities, Fair Value	$ 24,456	$ 7,412

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

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+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

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+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109979856&loc=d3e26610-111562

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