Investments (Tables)

12 Months Ended

Dec. 31, 2011

Investment [Abstract]

Fixed Income Securities Available For Sale

		Available for sale
		Cost or		Gross		Gross
		amortized		unrealized		unrealized
		cost		gain		loss		Fair value
December 31, 2011
U.S. government and government agency securities		$	285,166	$	10,523	$	(10)	$	295,679
Fixed income securities of states, municipalities and political
	subdivisions		999,940		85,528		(127)		1,085,341
Special purpose revenue bonds of states, municipalities and
	political subdivisions		1,741,297		122,746		(155)		1,863,888
Corporate fixed income securities			817,886		35,221		(6,774)		846,333
Residential mortgage-backed securities			1,036,436		65,771		(2,121)		1,100,086
Commercial mortgage-backed securities			244,535		15,162		(3,573)		256,124
Asset-backed securities			34,655		147		(56)		34,746
Foreign government securities			225,517		11,203		(83)		236,637
	Total fixed income securities - available for sale	$	5,385,432	$	346,301	$	(12,899)	$	5,718,834

		Available for sale
		Cost or		Gross		Gross
		amortized		unrealized		unrealized
		cost		gain		loss		Fair value
December 31, 2010
U.S. government and government agency securities		$	315,339	$	9,097	$	(169)	$	324,267
Fixed income securities of states, municipalities and political
	subdivisions		1,050,969		38,825		(7,737)		1,082,057
Special purpose revenue bonds of states, municipalities and
	political subdivisions		1,614,554		34,764		(21,259)		1,628,059
Corporate fixed income securities			545,883		26,436		(1,925)		570,394
Residential mortgage-backed securities			958,404		40,949		(4,245)		995,108
Commercial mortgage-backed securities			136,746		8,518		(36)		145,228
Asset-backed securities			12,563		78		(75)		12,566
Foreign government securities			230,348		11,537		(124)		241,761
	Total fixed income securities - available for sale	$	4,864,806	$	170,204	$	(35,570)	$	4,999,440

Fixed Income Securities Held To Maturity

		Held to maturity
		Cost or		Gross		Gross
		amortized		unrealized		unrealized
		cost		gain		loss		Fair value
December 31, 2011
U.S. government securities		$	6,998	$	69	$	-	$	7,067
Corporate fixed income securities			110,284		1,814		(455)		111,643
Foreign government securities			43,820		746		(140)		44,426
	Total fixed income securities - held to maturity	$	161,102	$	2,629	$	(595)	$	163,136

December 31, 2010
U.S. government securities		$	12,993	$	264	$	-	$	13,257
Corporate fixed income securities			113,296		1,205		(277)		114,224
Foreign government securities			67,379		995		(44)		68,330
	Total fixed income securities - held to maturity	$	193,668	$	2,464	$	(321)	$	195,811

Gross unrealized losses and fair value of all available for sale fixed income securities loss that were in a continuous loss position

		Less than 12 months				12 months or more				Total
				Unrealized				Unrealized				Unrealized
		Fair value		losses		Fair value		losses		Fair value		losses
December 31, 2011
U.S. government and government agency
	securities	$	13,984	$	(10)	$	0	$	0	$	13,984	$	(10)
Fixed income securities of states,
	municipalities and political subdivisions		10,256		(107)		899		(20)		11,155		(127)
Special purpose revenue bonds of states,
	municipalities and political subdivisions		21,856		(67)		6,796		(88)		28,652		(155)
Corporate fixed income securities			154,856		(6,391)		18,005		(383)		172,861		(6,774)
Residential mortgage-backed securities			32,430		(1,364)		7,582		(757)		40,012		(2,121)
Commercial mortgage-backed securities			39,075		(3,573)		0		0		39,075		(3,573)
Asset-backed securities			19,648		(56)		0		0		19,648		(56)
Foreign government securities			4,198		(83)		0		0		4,198		(83)
	Total	$	296,303	$	(11,651)	$	33,282	$	(1,248)	$	329,585	$	(12,899)

December 31, 2010
U.S. government and government agency
	securities	$	20,976	$	(169)	$	0	$	0	$	20,976	$	(169)
Fixed income securities of states,
	municipalities and political subdivisions		228,228		(7,621)		2,279		(116)		230,507		(7,737)
Special purpose revenue bonds of states,
	municipalities and political subdivisions		689,190		(21,156)		6,344		(103)		695,534		(21,259)
Corporate fixed income securities			66,029		(1,925)		0		0		66,029		(1,925)
Residential mortgage-backed securities			123,782		(3,081)		22,152		(1,164)		145,934		(4,245)
Commercial mortgage-backed securities			0		0		3,084		(36)		3,084		(36)
Asset-backed securities			9,174		(75)		0		0		9,174		(75)
Foreign government securities			10,699		(124)		0		0		10,699		(124)
	Total	$	1,148,078	$	(34,151)	$	33,859	$	(1,419)	$	1,181,937	$	(35,570)

Other than temporary impairment

		2011		2010		2009
Total other-than-temporary impairment loss		$	(6,922)	$	(378)	$	(6,443)
Portion recognized in other comprehensive income			2,243		(47)		1,014
	Net other-than-temporary impairment loss
	recognized in earnings	$	(4,679)	$	(425)	$	(5,429)

Rollforward of other than temporary impairment credit losses

	2011		2010
Balance at beginning of year	$	4,273	$	3,848
Credit losses recognized in earnings
Securities previously impaired		2,447		425
Securities previously not impaired		2,232		0
Securities sold		(3,905)		0
Balance at December 31	$	5,047	$	4,273

Amortized cost and fair value of fixed income securities

		Available for sale				Held to maturity
		Cost or amortized cost		Fair value		Amortized cost		Fair value
Due in 1 year or less		$	259,072	$	264,361	$	63,127	$	63,340
Due after 1 year through 5 years			1,086,817		1,133,474		97,137		98,874
Due after 5 years through 10 years			1,093,709		1,189,777		838		922
Due after 10 years through 15 years			753,856		818,232		0		0
Due after 15 years			876,352		922,034		0		0
	Securities with fixed maturities		4,069,806		4,327,878		161,102		163,136
Mortgage-backed and asset-backed securities			1,315,626		1,390,956		0		0
	Total fixed income securities	$	5,385,432	$	5,718,834	$	161,102	$	163,136

Change in Unrealized Gain (Loss) on Investments

		2011		2010		2009
Available for sale fixed income securities		$	198,768	$	(21,677)	$	141,685
Other investments			(2,351)		20		(2)
	Change in net unrealized investment gains (losses)	$	196,417	$	(21,657)	$	141,683