Investments (Details 1) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Gross unrealized losses and fair value of all available for sale securities that were in a continuous loss position
Less than 12 months, Fair value	$ 806,757	$ 1,913,235
Less than 12 months, Unrealized losses	(27,841)	(85,659)
12 months or more, Fair value	617,224	171,280
12 months or more, Unrealized losses	(13,935)	(19,562)
Total, Fair value	1,423,981	2,084,515
Total, Unrealized losses	(41,776)	(105,221)
US Government and Government Agency Securities [Member]
Gross unrealized losses and fair value of all available for sale securities that were in a continuous loss position
Less than 12 months, Fair value	14,813	23,717
Less than 12 months, Unrealized losses	(8)	(495)
12 months or more, Fair value	11,236	0
12 months or more, Unrealized losses	(129)	0
Total, Fair value	26,049	23,717
Total, Unrealized losses	(137)	(495)
Fixed Maturity Securities of States, Municipalities and Political Subdivisions Securities [Member]
Gross unrealized losses and fair value of all available for sale securities that were in a continuous loss position
Less than 12 months, Fair value	3,857	136,160
Less than 12 months, Unrealized losses	(21)	(5,277)
12 months or more, Fair value	19,337	8,997
12 months or more, Unrealized losses	(139)	(702)
Total, Fair value	23,194	145,157
Total, Unrealized losses	(160)	(5,979)
Special Purpose Revenue Bonds Of States Municipalities And Political Subdivisions [Member]
Gross unrealized losses and fair value of all available for sale securities that were in a continuous loss position
Less than 12 months, Fair value	4,041	684,560
Less than 12 months, Unrealized losses	(19)	(35,832)
12 months or more, Fair value	100,947	83,228
12 months or more, Unrealized losses	(967)	(10,926)
Total, Fair value	104,988	767,788
Total, Unrealized losses	(986)	(46,758)
Corporate Securities [Member]
Gross unrealized losses and fair value of all available for sale securities that were in a continuous loss position
Less than 12 months, Fair value	393,274	277,853
Less than 12 months, Unrealized losses	(7,085)	(8,202)
12 months or more, Fair value	69,662	35,437
12 months or more, Unrealized losses	(4,464)	(2,807)
Total, Fair value	462,936	313,290
Total, Unrealized losses	(11,549)	(11,009)
Residential Mortgage Backed Securities [Member]
Gross unrealized losses and fair value of all available for sale securities that were in a continuous loss position
Less than 12 months, Fair value	37,434	306,874
Less than 12 months, Unrealized losses	(100)	(15,861)
12 months or more, Fair value	226,256	31,687
12 months or more, Unrealized losses	(3,879)	(4,075)
Total, Fair value	263,690	338,561
Total, Unrealized losses	(3,979)	(19,936)
Commercial Mortgage Backed Securities [Member]
Gross unrealized losses and fair value of all available for sale securities that were in a continuous loss position
Less than 12 months, Fair value	5,228	203,347
Less than 12 months, Unrealized losses	(26)	(12,611)
12 months or more, Fair value	99,868	4,915
12 months or more, Unrealized losses	(2,006)	(725)
Total, Fair value	105,096	208,262
Total, Unrealized losses	(2,032)	(13,336)
Asset-backed Securities [Member]
Gross unrealized losses and fair value of all available for sale securities that were in a continuous loss position
Less than 12 months, Fair value	181,579	126,922
Less than 12 months, Unrealized losses	(1,245)	(1,587)
12 months or more, Fair value	78,797	0
12 months or more, Unrealized losses	(1,347)	0
Total, Fair value	260,376	126,922
Total, Unrealized losses	(2,592)	(1,587)
Foreign Government Securities [Member]
Gross unrealized losses and fair value of all available for sale securities that were in a continuous loss position
Less than 12 months, Fair value	55,280	78,182
Less than 12 months, Unrealized losses	(1,498)	(357)
12 months or more, Fair value	7,187	0
12 months or more, Unrealized losses	(56)	0
Total, Fair value	62,467	78,182
Total, Unrealized losses	(1,554)	(357)
Equity Securities [Member]
Gross unrealized losses and fair value of all available for sale securities that were in a continuous loss position
Less than 12 months, Fair value	111,251	75,620
Less than 12 months, Unrealized losses	(17,839)	(5,437)
12 months or more, Fair value	3,934	7,016
12 months or more, Unrealized losses	(948)	(327)
Total, Fair value	115,185	82,636
Total, Unrealized losses	$ (18,787)	$ (5,764)