Investments (Details 3) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014 Number	Dec. 31, 2013 Number
Fixed maturity securities Fair Value
Fixed maturity securities, Fair Value 12 Months or Less	$ 746,584	$ 1,672,852
Fixed maturity securities, Fair Value More than 12 Months	388,536	83,093
Fixed maturity securities, Fair Value, Total	1,135,120	1,755,945
Fixed maturity securities Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses 12 Months or Less	14,482	108,594
Fixed maturity securities, Gross Unrealized Losses More than 12 Months	14,941	13,943
Fixed maturity securities, Gross Unrealized Losses, Total	29,423	122,537
Number of positions with a gross unrealized loss 12 months or less	234	534
Number of position with gross unrealized loss position more than 12 months	112	46
Number of position with gross unrealized loss position Total	346	580
Fair value as percentage of fixed maturities and equity securities fair value less than 12 months	10.70%	27.40%
Fair value as percentage of fixed maturities and equity securities fair value more than 12 months	5.50%	1.40%
Fair value as percentage of fixed maturities and equity securities fair value, Total	16.20%	28.80%
Mortgage-backed securities [Member]
Fixed maturity securities Fair Value
Fixed maturity securities, Fair Value 12 Months or Less	2	150,602
Fixed maturity securities, Fair Value More than 12 Months	39,809	1,383
Fixed maturity securities, Fair Value, Total	39,811	151,985
Fixed maturity securities Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses 12 Months or Less	0	19,145
Fixed maturity securities, Gross Unrealized Losses More than 12 Months	1,390	415
Fixed maturity securities, Gross Unrealized Losses, Total	1,390	19,560
Other [Member]
Fixed maturity securities Fair Value
Fixed maturity securities, Fair Value 12 Months or Less	10,317	249,765
Fixed maturity securities, Fair Value More than 12 Months	117,615	4,450
Fixed maturity securities, Fair Value, Total	127,932	254,215
Fixed maturity securities Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses 12 Months or Less	34	22,479
Fixed maturity securities, Gross Unrealized Losses More than 12 Months	3,015	872
Fixed maturity securities, Gross Unrealized Losses, Total	3,049	23,351
Municipal Bonds [Member]
Fixed maturity securities Fair Value
Fixed maturity securities, Fair Value 12 Months or Less	31,821	375,523
Fixed maturity securities, Fair Value More than 12 Months	59,715	42,899
Fixed maturity securities, Fair Value, Total	91,536	418,422
Fixed maturity securities Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses 12 Months or Less	200	26,529
Fixed maturity securities, Gross Unrealized Losses More than 12 Months	4,228	8,086
Fixed maturity securities, Gross Unrealized Losses, Total	4,428	34,615
Foreign government bonds [Member]
Fixed maturity securities Fair Value
Fixed maturity securities, Fair Value 12 Months or Less	0	6,738
Fixed maturity securities, Fair Value More than 12 Months	0	0
Fixed maturity securities, Fair Value, Total	0	6,738
Fixed maturity securities Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses 12 Months or Less	0	390
Fixed maturity securities, Gross Unrealized Losses More than 12 Months	0	0
Fixed maturity securities, Gross Unrealized Losses, Total	0	390
Corporate Bonds [Member]
Fixed maturity securities Fair Value
Fixed maturity securities, Fair Value 12 Months or Less	213,612	582,849
Fixed maturity securities, Fair Value More than 12 Months	76,099	12,948
Fixed maturity securities, Fair Value, Total	289,711	595,797
Fixed maturity securities Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses 12 Months or Less	6,883	28,634
Fixed maturity securities, Gross Unrealized Losses More than 12 Months	4,373	3,516
Fixed maturity securities, Gross Unrealized Losses, Total	11,256	32,150
Other Mortgage-backed Securities [Member]
Fixed maturity securities Fair Value
Fixed maturity securities, Fair Value 12 Months or Less	477,877	274,983
Fixed maturity securities, Fair Value More than 12 Months	88,663	20,008
Fixed maturity securities, Fair Value, Total	566,540	294,991
Fixed maturity securities Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses 12 Months or Less	4,797	8,300
Fixed maturity securities, Gross Unrealized Losses More than 12 Months	1,095	552
Fixed maturity securities, Gross Unrealized Losses, Total	5,892	8,852
Total Fixed Maturities Securities [Member]
Fixed maturity securities Fair Value
Fixed maturity securities, Fair Value 12 Months or Less	733,629	1,640,460
Fixed maturity securities, Fair Value More than 12 Months	381,901	81,688
Fixed maturity securities, Fair Value, Total	1,115,530	1,722,148
Fixed maturity securities Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses 12 Months or Less	11,914	105,477
Fixed maturity securities, Gross Unrealized Losses More than 12 Months	14,101	13,441
Fixed maturity securities, Gross Unrealized Losses, Total	26,015	118,918
Equity Securities [Member]
Fixed maturity securities Fair Value
Fixed maturity securities, Fair Value 12 Months or Less	12,955	32,392
Fixed maturity securities, Fair Value More than 12 Months	6,635	1,405
Fixed maturity securities, Fair Value, Total	19,590	33,797
Fixed maturity securities Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses 12 Months or Less	2,568	3,117
Fixed maturity securities, Gross Unrealized Losses More than 12 Months	840	502
Fixed maturity securities, Gross Unrealized Losses, Total	$ 3,408	$ 3,619

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