Note 5 - Investments Schedule of Unrealized Losses (Details) $ in Thousands	Sep. 30, 2015 USD ($) security	Dec. 31, 2014 USD ($) security
Continuous Loss Position Less Than Twelve Months
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | security	189	62
Fair value available-for-sale securities	$ 777,284	$ 144,626
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	$ 18,107	$ 2,379
Continuous Unrealized Loss Position, Twelve Months Or Greater
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year | security	23	2
Fair value available-for-sale securities	$ 52,379	$ 4,482
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 1,964	$ 154
Continuous Loss Position, Total
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | security	212	64
Fair value available-for-sale securities	$ 829,663	$ 149,108
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 20,071	$ 2,533
US government and agency securities
Continuous Loss Position Less Than Twelve Months
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | security		0
Fair value available-for-sale securities		$ 0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss		$ 0
Continuous Unrealized Loss Position, Twelve Months Or Greater
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year | security		1
Fair value available-for-sale securities		$ 3,455
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		$ 6
Continuous Loss Position, Total
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | security		1
Fair value available-for-sale securities		$ 3,455
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		$ 6
Corporate bonds and notes
Continuous Loss Position Less Than Twelve Months
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | security	77	24
Fair value available-for-sale securities	$ 307,644	$ 40,917
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	$ 11,689	$ 410
Continuous Unrealized Loss Position, Twelve Months Or Greater
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year | security	6	1
Fair value available-for-sale securities	$ 8,716	$ 1,027
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 439	$ 148
Continuous Loss Position, Total
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | security	83	25
Fair value available-for-sale securities	$ 316,360	$ 41,944
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 12,128	$ 558
RMBS
Continuous Loss Position Less Than Twelve Months
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | security	6
Fair value available-for-sale securities	$ 70,121
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	$ 360
Continuous Unrealized Loss Position, Twelve Months Or Greater
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year | security	0
Fair value available-for-sale securities	$ 0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 0
Continuous Loss Position, Total
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | security	6
Fair value available-for-sale securities	$ 70,121
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 360
CMBS
Continuous Loss Position Less Than Twelve Months
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | security	30
Fair value available-for-sale securities	$ 179,673
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	$ 3,049
Continuous Unrealized Loss Position, Twelve Months Or Greater
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year | security	0
Fair value available-for-sale securities	$ 0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 0
Continuous Loss Position, Total
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | security	30
Fair value available-for-sale securities	$ 179,673
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 3,049
Other ABS
Continuous Loss Position Less Than Twelve Months
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | security	62	34
Fair value available-for-sale securities	$ 205,452	$ 97,356
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	$ 2,038	$ 1,727
Continuous Unrealized Loss Position, Twelve Months Or Greater
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year | security	13	0
Fair value available-for-sale securities	$ 42,127	$ 0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 1,290	$ 0
Continuous Loss Position, Total
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | security	75	34
Fair value available-for-sale securities	$ 247,579	$ 97,356
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 3,328	$ 1,727
Foreign government securities
Continuous Loss Position Less Than Twelve Months
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | security	14	4
Fair value available-for-sale securities	$ 14,394	$ 6,353
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	$ 971	$ 242
Continuous Unrealized Loss Position, Twelve Months Or Greater
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year | security	4	0
Fair value available-for-sale securities	$ 1,536	$ 0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 235	$ 0
Continuous Loss Position, Total
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | security	18	4
Fair value available-for-sale securities	$ 15,930	$ 6,353
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 1,206	$ 242