Investments (Details 1) (USD $) In Thousands, unless otherwise specified	6 Months Ended		12 Months Ended
	Jun. 30, 2013		Dec. 31, 2012
Fixed maturity securities Fair Value
Fixed maturity securities, Fair Value 12 Months or Less	$ 1,340,259		$ 263,571
Fixed maturity securities, Fair Value More than 12 Months	60,009		55,788
Fixed maturity securities, Fair Value, Total	1,400,268		319,359
Fixed maturity securities Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses 12 Months or Less	70,090		5,648
Fixed maturity securities, Gross Unrealized Losses More than 12 Months	5,890		5,532
Fixed maturity securities, Gross Unrealized Losses, Total	75,980		11,180
Number of positions with a gross unrealized loss 12 months or less	435		156
Number of position with gross unrealized loss position more than 12 months	33		43
Number of position with gross unrealized loss position, Total	468		199
Fair value as percentage of total fixed maturities and equity securities fair value less than 12 months	22.30%		4.40%
Fair value as percentage of total fixed maturities and equity securities fair value more than 12 months	1.00%		0.90%
Fair value as percentage of total fixed maturities and equity securities fair value, Total	23.30%		5.30%
Mortgage-backed securities [Member]
Fixed maturity securities Fair Value
Fixed maturity securities, Fair Value 12 Months or Less	103,346		11,006
Fixed maturity securities, Fair Value More than 12 Months	44		50
Fixed maturity securities, Fair Value, Total	103,390		11,056
Fixed maturity securities Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses 12 Months or Less	6,165		124
Fixed maturity securities, Gross Unrealized Losses More than 12 Months	0		1
Fixed maturity securities, Gross Unrealized Losses, Total	6,165		125
Other [Member]
Fixed maturity securities Fair Value
Fixed maturity securities, Fair Value 12 Months or Less	167,405		9,944
Fixed maturity securities, Fair Value More than 12 Months	0		0
Fixed maturity securities, Fair Value, Total	167,405		9,944
Fixed maturity securities Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses 12 Months or Less	11,420		135
Fixed maturity securities, Gross Unrealized Losses More than 12 Months	0		0
Fixed maturity securities, Gross Unrealized Losses, Total	11,420		135
Municipal bonds [Member]
Fixed maturity securities Fair Value
Fixed maturity securities, Fair Value 12 Months or Less	302,729		108,578
Fixed maturity securities, Fair Value More than 12 Months	9,551		3,990
Fixed maturity securities, Fair Value, Total	312,280		112,568
Fixed maturity securities Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses 12 Months or Less	19,486		2,605
Fixed maturity securities, Gross Unrealized Losses More than 12 Months	837		43
Fixed maturity securities, Gross Unrealized Losses, Total	20,323		2,648
Foreign government bonds [Member]
Fixed maturity securities Fair Value
Fixed maturity securities, Fair Value 12 Months or Less	5,762		0
Fixed maturity securities, Fair Value More than 12 Months	0		0
Fixed maturity securities, Fair Value, Total	5,762		0
Fixed maturity securities Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses 12 Months or Less	216		0
Fixed maturity securities, Gross Unrealized Losses More than 12 Months	0		0
Fixed maturity securities, Gross Unrealized Losses, Total	216		0
Corporate bonds [Member]
Fixed maturity securities Fair Value
Fixed maturity securities, Fair Value 12 Months or Less	541,977		56,481
Fixed maturity securities, Fair Value More than 12 Months	13,749		26,725
Fixed maturity securities, Fair Value, Total	555,726		83,206
Fixed maturity securities Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses 12 Months or Less	24,891		875
Fixed maturity securities, Gross Unrealized Losses More than 12 Months	3,484		4,075
Fixed maturity securities, Gross Unrealized Losses, Total	28,375		4,950
Other mortgage-backed securities [Member]
Fixed maturity securities Fair Value
Fixed maturity securities, Fair Value 12 Months or Less	189,646		58,218
Fixed maturity securities, Fair Value More than 12 Months	35,632		25,014
Fixed maturity securities, Fair Value, Total	225,278		83,232
Fixed maturity securities Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses 12 Months or Less	6,986		621
Fixed maturity securities, Gross Unrealized Losses More than 12 Months	1,146		1,411
Fixed maturity securities, Gross Unrealized Losses, Total	8,132		2,032
Total fixed maturities securities [Member]
Fixed maturity securities Fair Value
Fixed maturity securities, Fair Value 12 Months or Less	1,310,865		244,227
Fixed maturity securities, Fair Value More than 12 Months	58,976		55,779
Fixed maturity securities, Fair Value, Total	1,369,841		300,006
Fixed maturity securities Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses 12 Months or Less	69,164		4,360
Fixed maturity securities, Gross Unrealized Losses More than 12 Months	5,467		5,530
Fixed maturity securities, Gross Unrealized Losses, Total	74,631		9,890
Equity securities [Member]
Fixed maturity securities Fair Value
Fixed maturity securities, Fair Value 12 Months or Less	29,394	[1]	19,344	[1]
Fixed maturity securities, Fair Value More than 12 Months	1,033	[1]	9	[1]
Fixed maturity securities, Fair Value, Total	30,427	[1]	19,353	[1]
Fixed maturity securities Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses 12 Months or Less	926	[1]	1,288	[1]
Fixed maturity securities, Gross Unrealized Losses More than 12 Months	423	[1]	2	[1]
Fixed maturity securities, Gross Unrealized Losses, Total	$ 1,349	[1]	$ 1,290	[1]

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