Investments (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2014 Number		Dec. 31, 2013 Number
Fixed maturity securities Fair Value
Fixed maturity securities, Fair Value 12 Months or Less	$ 1,212,661		$ 1,672,852
Fixed maturity securities, Fair Value More than 12 Months	146,745		83,093
Fixed maturity securities, Fair Value, Total	1,359,406		1,755,945
Fixed maturity securities Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses 12 Months or Less	53,571		108,594
Fixed maturity securities, Gross Unrealized Losses More than 12 Months	15,703		13,943
Fixed maturity securities, Gross Unrealized Losses, Total	69,274		122,537
Number of positions with a gross unrealized loss position 12 Months or Less	359		534
Number of position with a gross unrealized loss position more than 12 months	61		46
Number of position with a gross unrealized loss position, Total	420		580
Fair value as a percentage of total fixed maturities and equity securities fair value 12 Months or Less	18.70%		27.40%
Fair value as a percentage of total fixed maturities and equity securities fair value more than 12 months	2.30%		1.40%
Fair value as a percentage of total fixed maturities and equity securities fair value, Total	20.90%		28.80%
Mortgage-backed securities [Member]
Fixed maturity securities Fair Value
Fixed maturity securities, Fair Value 12 Months or Less	111,266		150,602
Fixed maturity securities, Fair Value More than 12 Months	7,787		1,383
Fixed maturity securities, Fair Value, Total	119,053		151,985
Fixed maturity securities Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses 12 Months or Less	11,450		19,145
Fixed maturity securities, Gross Unrealized Losses More than 12 Months	1,343		415
Fixed maturity securities, Gross Unrealized Losses, Total	12,793		19,560
Other [Member]
Fixed maturity securities Fair Value
Fixed maturity securities, Fair Value 12 Months or Less	179,661		249,765
Fixed maturity securities, Fair Value More than 12 Months	17,164		4,450
Fixed maturity securities, Fair Value, Total	196,825		254,215
Fixed maturity securities Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses 12 Months or Less	12,184		22,479
Fixed maturity securities, Gross Unrealized Losses More than 12 Months	2,319		872
Fixed maturity securities, Gross Unrealized Losses, Total	14,503		23,351
Municipal bonds [Member]
Fixed maturity securities Fair Value
Fixed maturity securities, Fair Value 12 Months or Less	211,712		375,523
Fixed maturity securities, Fair Value More than 12 Months	59,942		42,899
Fixed maturity securities, Fair Value, Total	271,654		418,422
Fixed maturity securities Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses 12 Months or Less	9,707		26,529
Fixed maturity securities, Gross Unrealized Losses More than 12 Months	6,175		8,086
Fixed maturity securities, Gross Unrealized Losses, Total	15,882		34,615
Foreign government bonds [Member]
Fixed maturity securities Fair Value
Fixed maturity securities, Fair Value 12 Months or Less	6,965		6,738
Fixed maturity securities, Fair Value More than 12 Months	0		0
Fixed maturity securities, Fair Value, Total	6,965		6,738
Fixed maturity securities Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses 12 Months or Less	157		390
Fixed maturity securities, Gross Unrealized Losses More than 12 Months	0		0
Fixed maturity securities, Gross Unrealized Losses, Total	157		390
Corporate bonds [Member]
Fixed maturity securities Fair Value
Fixed maturity securities, Fair Value 12 Months or Less	412,997		582,849
Fixed maturity securities, Fair Value More than 12 Months	17,263		12,948
Fixed maturity securities, Fair Value, Total	430,260		595,797
Fixed maturity securities Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses 12 Months or Less	13,845		28,634
Fixed maturity securities, Gross Unrealized Losses More than 12 Months	3,157		3,516
Fixed maturity securities, Gross Unrealized Losses, Total	17,002		32,150
Other mortgage-backed securities [Member]
Fixed maturity securities Fair Value
Fixed maturity securities, Fair Value 12 Months or Less	258,328		274,983
Fixed maturity securities, Fair Value More than 12 Months	43,116		20,008
Fixed maturity securities, Fair Value, Total	301,444		294,991
Fixed maturity securities Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses 12 Months or Less	4,223		8,300
Fixed maturity securities, Gross Unrealized Losses More than 12 Months	2,214		552
Fixed maturity securities, Gross Unrealized Losses, Total	6,437		8,852
Total fixed maturities securities [Member]
Fixed maturity securities Fair Value
Fixed maturity securities, Fair Value 12 Months or Less	1,180,929		1,640,460
Fixed maturity securities, Fair Value More than 12 Months	145,272		81,688
Fixed maturity securities, Fair Value, Total	1,326,201		1,722,148
Fixed maturity securities Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses 12 Months or Less	51,566		105,477
Fixed maturity securities, Gross Unrealized Losses More than 12 Months	15,208		13,441
Fixed maturity securities, Gross Unrealized Losses, Total	66,774		118,918
Equity securities [Member]
Fixed maturity securities Fair Value
Fixed maturity securities, Fair Value 12 Months or Less	31,732	[1]	32,392	[1]
Fixed maturity securities, Fair Value More than 12 Months	1,473	[1]	1,405	[1]
Fixed maturity securities, Fair Value, Total	33,205	[1]	33,797	[1]
Fixed maturity securities Gross Unrealized Losses
Fixed maturity securities, Gross Unrealized Losses 12 Months or Less	2,005	[1]	3,117	[1]
Fixed maturity securities, Gross Unrealized Losses More than 12 Months	495	[1]	502	[1]
Fixed maturity securities, Gross Unrealized Losses, Total	$ 2,500	[1]	$ 3,619	[1]

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