Investments (Details 3) $ in Thousands		Dec. 31, 2015 USD ($) Number	Dec. 31, 2014 USD ($) Number
Fixed maturity securities, Fair Value
Fixed maturity securities, Fair Value, 12 Months or Less		$ 2,304,060	$ 746,584
Fixed maturity securities, Fair Value, More than 12 Months		224,513	388,536
Fixed maturity securities, Fair Value, Total		2,528,573	1,135,120
Fixed maturity securities, Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses, 12 Months or Less		74,011	14,482
Fixed maturity securities, Gross Unrealized Losses, More than 12 Months		19,842	14,941
Fixed maturity securities, Gross Unrealized Losses, Total		$ 93,853	$ 29,423
Number of positions with a gross unrealized loss position, 12 Months or Less | Number		684	234
Number of position with a gross unrealized loss position, more than 12 months | Number		78	112
Number of position with a gross unrealized loss position, Total | Number		762	346
Fair value as a percentage of total fixed maturities and equity securities fair value, 12 Months or Less		32.00%	10.70%
Fair value as a percentage of total fixed maturities and equity securities fair value, more than 12 months		3.10%	5.50%
Fair value as a percentage of total fixed maturities and equity securities fair value, Total		35.10%	16.20%
Mortgage-backed securities [Member]
Fixed maturity securities, Fair Value
Fixed maturity securities, Fair Value, 12 Months or Less		$ 48,097	$ 2
Fixed maturity securities, Fair Value, More than 12 Months		1,595	39,809
Fixed maturity securities, Fair Value, Total		49,692	39,811
Fixed maturity securities, Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses, 12 Months or Less		1,748	0
Fixed maturity securities, Gross Unrealized Losses, More than 12 Months		113	1,390
Fixed maturity securities, Gross Unrealized Losses, Total		1,861	1,390
Other [Member]
Fixed maturity securities, Fair Value
Fixed maturity securities, Fair Value, 12 Months or Less		248,478	10,317
Fixed maturity securities, Fair Value, More than 12 Months		1,921	117,615
Fixed maturity securities, Fair Value, Total		250,399	127,932
Fixed maturity securities, Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses, 12 Months or Less		7,338	34
Fixed maturity securities, Gross Unrealized Losses, More than 12 Months		77	3,015
Fixed maturity securities, Gross Unrealized Losses, Total		7,415	3,049
Municipal bonds [Member]
Fixed maturity securities, Fair Value
Fixed maturity securities, Fair Value, 12 Months or Less		168,939	31,821
Fixed maturity securities, Fair Value, More than 12 Months		21,717	59,715
Fixed maturity securities, Fair Value, Total		190,656	91,536
Fixed maturity securities, Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses, 12 Months or Less		5,382	200
Fixed maturity securities, Gross Unrealized Losses, More than 12 Months		4,958	4,228
Fixed maturity securities, Gross Unrealized Losses, Total		10,340	4,428
Foreign government bonds [Member]
Fixed maturity securities, Fair Value
Fixed maturity securities, Fair Value, 12 Months or Less		11,867	0
Fixed maturity securities, Fair Value, More than 12 Months		0	0
Fixed maturity securities, Fair Value, Total		11,867	0
Fixed maturity securities, Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses, 12 Months or Less		112	0
Fixed maturity securities, Gross Unrealized Losses, More than 12 Months		0	0
Fixed maturity securities, Gross Unrealized Losses, Total		112	0
Corporate bonds [Member]
Fixed maturity securities, Fair Value
Fixed maturity securities, Fair Value, 12 Months or Less		858,647	213,612
Fixed maturity securities, Fair Value, More than 12 Months		50,340	76,099
Fixed maturity securities, Fair Value, Total		908,987	289,711
Fixed maturity securities, Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses, 12 Months or Less		37,244	6,883
Fixed maturity securities, Gross Unrealized Losses, More than 12 Months		11,590	4,373
Fixed maturity securities, Gross Unrealized Losses, Total		48,834	11,256
Other mortgage-backed securities [Member]
Fixed maturity securities, Fair Value
Fixed maturity securities, Fair Value, 12 Months or Less		929,268	477,877
Fixed maturity securities, Fair Value, More than 12 Months		140,561	88,663
Fixed maturity securities, Fair Value, Total		1,069,829	566,540
Fixed maturity securities, Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses, 12 Months or Less		19,165	4,797
Fixed maturity securities, Gross Unrealized Losses, More than 12 Months		1,796	1,095
Fixed maturity securities, Gross Unrealized Losses, Total		20,961	5,892
Total fixed maturity securities [Member]
Fixed maturity securities, Fair Value
Fixed maturity securities, Fair Value, 12 Months or Less		2,265,296	733,629
Fixed maturity securities, Fair Value, More than 12 Months		216,134	381,901
Fixed maturity securities, Fair Value, Total		2,481,430	1,115,530
Fixed maturity securities, Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses, 12 Months or Less		70,989	11,914
Fixed maturity securities, Gross Unrealized Losses, More than 12 Months		18,534	14,101
Fixed maturity securities, Gross Unrealized Losses, Total		89,523	26,015
Equity securities [Member]
Fixed maturity securities, Fair Value
Fixed maturity securities, Fair Value, 12 Months or Less	[1]	38,764	12,955
Fixed maturity securities, Fair Value, More than 12 Months	[1]	8,379	6,635
Fixed maturity securities, Fair Value, Total	[1]	47,143	19,590
Fixed maturity securities, Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses, 12 Months or Less	[1]	3,022	2,568
Fixed maturity securities, Gross Unrealized Losses, More than 12 Months	[1]	1,308	840
Fixed maturity securities, Gross Unrealized Losses, Total	[1]	$ 4,330	$ 3,408

[1] Includes nonredeemable (perpetual) preferred stocks, common stocks and closed-end funds.