Investments (Tables)

12 Months Ended

Dec. 31, 2012

Investment [Abstract]

Fixed Maturity & Equity Securities Available For Sale

		Available for sale
		Cost or		Gross		Gross
		amortized		unrealized		unrealized
		cost		gain		loss		Fair value
December 31, 2012
U.S. government and government agency securities		$	195,049	$	4,560	$	(2)	$	199,607
Fixed maturity securities of states, municipalities and political
	subdivisions		969,966		96,027		(182)		1,065,811
Special purpose revenue bonds of states, municipalities and
	political subdivisions		2,033,947		168,772		(2,388)		2,200,331
Corporate securities			1,247,282		69,243		(1,355)		1,315,170
Residential mortgage-backed securities			632,665		32,560		(338)		664,887
Commercial mortgage-backed securities			482,808		41,748		(267)		524,289
Asset-backed securities			32,801		474		0		33,275
Foreign government securities			261,914		16,515		(18)		278,411
	Total fixed maturity securities - available for sale	$	5,856,432	$	429,899	$	(4,550)	$	6,281,781
Equity securities - available for sale		$	275,827	$	13,768	$	(4,956)	$	284,639

		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 maturity 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 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 maturity securities - available for sale	$	5,385,432	$	346,301	$	(12,899)	$	5,718,834

Fixed Maturity Securities Held To Maturity

U.S. government securities		$	6,998	$	69	$	-	$	7,067
Corporate securities			110,284		1,814		(455)		111,643
Foreign government securities			43,820		746		(140)		44,426
	Total fixed maturity securities - held to maturity	$	161,102	$	2,629	$	(595)	$	163,136

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, 2012
Fixed maturity securities
	U.S. government and government agency
		securities		$	55,034	$	(2)	$	0	$	0	$	55,034	$	(2)
	Fixed maturity securities of states,
		municipalities and political subdivisions			14,162		(182)		0		0		14,162		(182)
	Special purpose revenue bonds of states,
		municipalities and political subdivisions			155,902		(2,388)		0		0		155,902		(2,388)
	Corporate securities				85,245		(1,220)		2,616		(135)		87,861		(1,355)
	Residential mortgage-backed securities				49,486		(338)		0		0		49,486		(338)
	Commercial mortgage-backed securities				26,263		(267)		0		0		26,263		(267)
	Foreign government securities				7,007		(18)		0		0		7,007		(18)
Equity securities					103,647		(4,956)		0		0		103,647		(4,956)
			Total	$	496,746	$	(9,371)	$	2,616	$	(135)	$	499,362	$	(9,506)

December 31, 2011
Fixed maturity securities
	U.S. government and government agency
		securities		$	13,984	$	(10)	$	0	$	0	$	13,984	$	(10)
	Fixed maturity 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 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)

Other than temporary impairment

		2012		2011		2010
Total other-than-temporary impairment loss		$	(2,069)	$	(6,922)	$	(378)
Portion recognized in other comprehensive income			1,041		2,243		(47)
	Net other-than-temporary impairment loss
	recognized in earnings	$	(1,028)	$	(4,679)	$	(425)

Rollforward of other than temporary impairment credit losses

	2012		2011		2010
Balance at beginning of year	$	5,047	$	4,273	$	3,848
Credit losses recognized in earnings
Securities previously impaired		899		2,447		425
Securities previously not impaired		129		2,232		0
Securities sold		(5,450)		(3,905)		0
Balance at December 31	$	625	$	5,047	$	4,273

Amortized cost and fair value of fixed maturity securities

		Available for sale
		Cost or amortized cost		Fair value
Due in 1 year or less		$	300,842	$	305,382
Due after 1 year through 5 years			1,101,203		1,157,575
Due after 5 years through 10 years			1,411,731		1,541,532
Due after 10 years through 15 years			936,809		1,023,796
Due after 15 years			957,573		1,031,045
	Securities with contractual maturities		4,708,158		5,059,330
Mortgage-backed and asset-backed securities			1,148,274		1,222,451
	Total fixed maturity securities	$	5,856,432	$	6,281,781

Change in Unrealized Gain (Loss) on Investments

		2012		2011		2010
Available for sale fixed maturity securities		$	91,947	$	198,768	$	(21,677)
Equity securities			8,812		0		0
Other investments			4,867		(2,351)		20
	Change in net unrealized investment gains (losses)	$	105,626	$	196,417	$	(21,657)