Investments Debt And Equity Securities (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Dec. 31, 2011
Investments Including Short Term And Cash And Cash Equivalents [Abstract]
Fixed maturity securities	$ 815,389		$ 791,528
Fixed maturity securities percent	84.10%		82.70%
Equity securities	54,029		53,741
Equity securities percent	5.60%		5.60%
Mortgage loans	1,376		1,509
Mortgage loans percent	0.10%		0.20%
Policy loans	44,872		42,993
Policy loans percent	4.60%		4.50%
Real estate and other long-term investments	8,559		8,553
Real estate and other long-term investments percent	0.90%		0.90%
Short-term investments	2,853		2,340
Short-term investments percent	0.30%		0.20%
Cash and cash equivalents	42,608	61,096	56,299	33,255
Cash and cash equivalents percent	4.40%		5.90%
Total cash, cash equivalents and investments	969,686		956,963
Total cash, cash equivalents and investments percent	100.00%		100.00%
Unrealized Gain (Loss) on Investments [Abstract]
Available-for-sale Debt Securities, Amortized Cost Basis	603,947		559,736
Available-for-sale Equity Securities, Amortized Cost Basis	52,553		52,744
Available-for-sale Securities, Debt Securities, Amortized Cost Basis, Total	603,947		559,736
Available-for-sale Debt Securities, Gross Unrealized Gains, Total	45,124		45,873
Available-for-sale Debt Securities, Gross Unrealized Losses, Total	1,389		1,089
Available-for-sale Debt Securities, Fair Value	647,682		604,520
Held-to-maturity Securities, Debt Securities, Net Carrying Amount	167,707		187,008
Held-to-maturity Securities, Unrecognized Holding Gain	7,559		7,109
Held-to-maturity Securities, Unrecognized Holding Loss	300		378
Held-to-maturity Securities, Debt Securities, Fair Value	174,966		193,739
Total Fixed Maturity Securities, Amortized Cost	771,654
Total Fixed Maturity Securities, Fair Value	822,648
Unrealized Continuous Losses on Investments [Abstract]
Number of Available-for-sale Securities In Continuous Loss Position Aggregate	125		90
Debt Securities In Continuous Loss Less Than 12 Months Fair Value	143,644		127,739
Debt Securities Continuous Loss Position Less Than 12 Months Unrealized Losses	1,347		1,131
Number of Debt Securities In Continuous Loss Less Than 12 Months	146		119
Debt Securities In Continuous Loss Position 12 Months Or Longer, Fair Value	6,464		5,151
Debt Securities In Continuous Loss Position 12 Months Or Longer, Unrealized Losses	342		336
Number of Debt Securities In Continuous Loss Position 12 Months or Longer	6		3
Debt Securities In Continuous Loss Position, Aggregate Fair Value	150,108		132,890
Debt Securities In Continuous Loss Position, Aggregate Unrealized Losses	1,689		1,467
Number of Debt Securities In Continuous Loss Position, Aggregate	152		122
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Proceeds from Sale of Available-for-sale Securities, Fixed Maturities	58	503
Proceeds from Sale of Available-for-sale Securities, Equity	0	0
Schedule of Fixed Maturities [Abstract]
Available-for-sale Securities, Debt Maturities, Due in One Year or Less, Amortized Cost Basis	235,637
Available-for-sale Securities, Debt Maturities, Due in One Year or Less, Fair Value	253,011
Available-for-sale Securities, Debt Maturities, Due After One Year Through Five Years, Amortized Cost Basis	81,964
Available-for-sale Securities, Debt Maturities, Due After One Year Through Five Years, Fair Value	88,031
Available-for-sale Securities, Debt Maturities, Due After Five Years Through Ten Years, Amortized Cost Basis	124,791
Available-for-sale Securities, Debt Maturities, Due After Five Years Through Ten Years, Fair Value	134,658
Available-for-sale Securities, Debt Maturities, Due After Ten Years, Amortized Cost Basis	156,350
Available-for-sale Securities, Debt Maturities, Due After Ten Years, Fair Value	166,335
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Amortized Cost Basis	5,205
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value	5,647
Held-to-maturity Securities, Debt Maturities, Due in One Year or Less, Amortized Cost Basis	13,236
Held-to-maturity Securities, Debt Maturities, Due in One Year or Less, Fair Value	13,349
Held-to-maturity Securities, Debt Maturities, Due After One Year Through Five Years, Amortized Cost Basis	34,427
Held-to-maturity Securities, Debt Maturities, Due After One Year Through Five Years, Fair Value	35,047
Held-to-maturity Securities, Debt Maturities, Due After Five Years Through Ten Years, Amortized Cost Basis	46,058
Held-to-maturity Securities, Debt Maturities, Due After Five Years Through Ten Years, Fair Value	49,283
Held-to-maturity Securities, Debt Maturities, Due After Ten Years, Amortized Cost Basis	73,986
Held-to-maturity Securities, Debt Maturities, Due After Ten Years, Fair Value	77,287
Sale of bonds, number of transactions of fixed maturity securities sold	1
Sale of bonds, number of securities sold at a loss	0
Sale of bonds, number of held-to-maturity bonds sold	0
US Treasury Securities [Member]
Unrealized Gain (Loss) on Investments [Abstract]
Available-for-sale Debt Securities, Amortized Cost Basis	10,155		10,170
Available-for-sale Securities, Gross Unrealized Gains	3,581		3,773
Available-for-sale Securities, Gross Unrealized Losses	0		0
Available-for-sale Securities, Fair Value	13,736		13,943
US Government Agencies Debt Securities [Member]
Unrealized Gain (Loss) on Investments [Abstract]
Available-for-sale Debt Securities, Amortized Cost Basis	69,444		81,788
Available-for-sale Securities, Gross Unrealized Gains	3,584		3,815
Available-for-sale Securities, Gross Unrealized Losses	14		22
Available-for-sale Securities, Fair Value	73,014		85,581
Held-to-maturity Securities, Debt Securities, Net Carrying Amount	16,482		28,632
Held-to-maturity Securities, Unrecognized Holding Gain	458		514
Held-to-maturity Securities, Unrecognized Holding Loss	0		0
Held-to-maturity Securities, Debt Securities, Fair Value	16,940		29,146
Unrealized Continuous Losses on Investments [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	1,673		10,603
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	14		22
Number of Available-for-sale Securities In Continuous Loss Position Less Than 12 Months	4		9
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0		0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0		0
Number of Available-for-sale Securities In Continuous Loss Position For 12 months or Greater	0		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,673		10,603
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	14		22
Number of Available-for-sale Securities In Continuous Loss Position Aggregate	4		9
US States and Political Subdivisions Debt Securities [Member]
Unrealized Gain (Loss) on Investments [Abstract]
Available-for-sale Debt Securities, Amortized Cost Basis	314,560		265,812
Available-for-sale Securities, Gross Unrealized Gains	17,756		17,227
Available-for-sale Securities, Gross Unrealized Losses	1,182		777
Available-for-sale Securities, Fair Value	331,134		282,262
Held-to-maturity Securities, Debt Securities, Net Carrying Amount	118,638		125,634
Held-to-maturity Securities, Unrecognized Holding Gain	5,957		5,435
Held-to-maturity Securities, Unrecognized Holding Loss	293		378
Held-to-maturity Securities, Debt Securities, Fair Value	124,302		130,691
Unrealized Continuous Losses on Investments [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	83,191		54,115
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	843		443
Number of Available-for-sale Securities In Continuous Loss Position Less Than 12 Months	97		61
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	6,365		5,099
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	339		334
Number of Available-for-sale Securities In Continuous Loss Position For 12 months or Greater	4		2
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	89,556		59,214
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	1,182		777
Number of Available-for-sale Securities In Continuous Loss Position Aggregate	101		63
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	26,685		40,611
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	293		378
Number of Held-to-maturity Securities In Continuous Loss Position Less Than 12 Months	25		32
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0		0
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0		0
Number of Held-to-maturity Securities In Continuous Loss Position 12 Months or Greater	0		0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	26,685		40,611
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Losses	293		378
Number of Held-to-maturity Securities In Continuous Loss Position Aggregate	25		32
Foreign Government Debt Securities [Member]
Unrealized Gain (Loss) on Investments [Abstract]
Available-for-sale Debt Securities, Amortized Cost Basis	105		105
Available-for-sale Securities, Gross Unrealized Gains	34		36
Available-for-sale Securities, Gross Unrealized Losses	0		0
Available-for-sale Securities, Fair Value	139		141
Corporate Debt Securities [Member]
Unrealized Gain (Loss) on Investments [Abstract]
Available-for-sale Debt Securities, Amortized Cost Basis	204,478		195,755
Available-for-sale Securities, Gross Unrealized Gains	19,724		20,536
Available-for-sale Securities, Gross Unrealized Losses	190		286
Available-for-sale Securities, Fair Value	224,012		216,005
Held-to-maturity Securities, Debt Securities, Net Carrying Amount	32,587		32,742
Held-to-maturity Securities, Unrecognized Holding Gain	1,144		1,160
Held-to-maturity Securities, Unrecognized Holding Loss	7		0
Held-to-maturity Securities, Debt Securities, Fair Value	33,724		33,902
Unrealized Continuous Losses on Investments [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	29,883		22,316
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	190		286
Number of Available-for-sale Securities In Continuous Loss Position Less Than 12 Months	18		16
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0		0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0		0
Number of Available-for-sale Securities In Continuous Loss Position For 12 months or Greater	0		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	29,883		22,316
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	190		286
Number of Available-for-sale Securities In Continuous Loss Position Aggregate	18		16
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	2,212
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	7
Number of Held-to-maturity Securities In Continuous Loss Position Less Than 12 Months	2
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0
Number of Held-to-maturity Securities In Continuous Loss Position 12 Months or Greater	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	2,212
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Losses	7
Number of Held-to-maturity Securities In Continuous Loss Position Aggregate	2
Collateralized Mortgage Backed Securities [Member]
Schedule of Fixed Maturities [Abstract]
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Amortized Cost Basis	5,200
Commercial Mortgage Backed Securities [Member]
Unrealized Gain (Loss) on Investments [Abstract]
Available-for-sale Debt Securities, Amortized Cost Basis	416		481
Available-for-sale Securities, Gross Unrealized Gains	16		17
Available-for-sale Securities, Gross Unrealized Losses	2		2
Available-for-sale Securities, Fair Value	430		496
Unrealized Continuous Losses on Investments [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	0		94
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	0		2
Number of Available-for-sale Securities In Continuous Loss Position Less Than 12 Months	0		1
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	48		0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	2		0
Number of Available-for-sale Securities In Continuous Loss Position For 12 months or Greater	1		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	48		94
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	2		2
Number of Available-for-sale Securities In Continuous Loss Position Aggregate	1		1
Residential Mortgage Backed Securities [Member]
Unrealized Gain (Loss) on Investments [Abstract]
Available-for-sale Debt Securities, Amortized Cost Basis	4,789		5,625
Available-for-sale Securities, Gross Unrealized Gains	429		469
Available-for-sale Securities, Gross Unrealized Losses	1		2
Available-for-sale Securities, Fair Value	5,217		6,092
Unrealized Continuous Losses on Investments [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	0		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	0		0
Number of Available-for-sale Securities In Continuous Loss Position Less Than 12 Months	0		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	51		52
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	1		2
Number of Available-for-sale Securities In Continuous Loss Position For 12 months or Greater	1		1
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	51		52
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	1		2
Number of Available-for-sale Securities In Continuous Loss Position Aggregate	1		1
Debt Securities [Member]
Unrealized Gain (Loss) on Investments [Abstract]
Total Fixed Maturity Securities, Amortized Cost	771,654		746,744
Total Fixed Maturity Securities, Gross Unrealized Gains	52,683		52,982
Total Fixed Maturity Securities, Gross Unrealized Losses	1,689		1,467
Total Fixed Maturity Securities, Fair Value	822,648		798,259
Unrealized Continuous Losses on Investments [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	114,747		87,128
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	1,047		753
Number of Available-for-sale Securities In Continuous Loss Position Less Than 12 Months	119		87
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	6,464		5,151
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	342		336
Number of Available-for-sale Securities In Continuous Loss Position For 12 months or Greater	6		3
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	121,211		92,279
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	1,389		1,089
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	28,897		40,611
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	300		378
Number of Held-to-maturity Securities In Continuous Loss Position Less Than 12 Months	27		32
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0		0
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0		0
Number of Held-to-maturity Securities In Continuous Loss Position 12 Months or Greater	0		0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	28,897		40,611
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Losses	300		378
Number of Held-to-maturity Securities In Continuous Loss Position Aggregate	27		32
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Available-for-sale Securities, Gross Realized Gains	1	1
Available-for-sale Securities, Gross Realized Losses	0	0
Stock Mutual Funds [Member]
Unrealized Gain (Loss) on Investments [Abstract]
Available-for-sale Equity Securities, Amortized Cost Basis	10,463		10,463
Available-for-sale Securities, Gross Unrealized Gains	905		250
Available-for-sale Securities, Gross Unrealized Losses	0		28
Available-for-sale Securities, Fair Value	11,368		10,685
Unrealized Continuous Losses on Investments [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value			0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses			0
Number of Available-for-sale Securities In Continuous Loss Position Less Than 12 Months			0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value			972
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses			28
Number of Available-for-sale Securities In Continuous Loss Position For 12 months or Greater			1
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value			972
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses			28
Number of Available-for-sale Securities In Continuous Loss Position Aggregate			1
Bond Mutual Funds [Member]
Unrealized Gain (Loss) on Investments [Abstract]
Available-for-sale Equity Securities, Amortized Cost Basis	41,504		41,504
Available-for-sale Securities, Gross Unrealized Gains	396		541
Available-for-sale Securities, Gross Unrealized Losses	185		129
Available-for-sale Securities, Fair Value	41,715		41,916
Unrealized Continuous Losses on Investments [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	9,301		3,335
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	123		88
Number of Available-for-sale Securities In Continuous Loss Position Less Than 12 Months	2		1
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	2,938		2,959
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	62		41
Number of Available-for-sale Securities In Continuous Loss Position For 12 months or Greater	2		2
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	12,239		6,294
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	185		129
Number of Available-for-sale Securities In Continuous Loss Position Aggregate	4		3
Common Stock [Member]
Unrealized Gain (Loss) on Investments [Abstract]
Available-for-sale Equity Securities, Amortized Cost Basis	17		17
Available-for-sale Securities, Gross Unrealized Gains	0		0
Available-for-sale Securities, Gross Unrealized Losses	2		2
Available-for-sale Securities, Fair Value	15		15
Unrealized Continuous Losses on Investments [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	15		15
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	2		2
Number of Available-for-sale Securities In Continuous Loss Position Less Than 12 Months	1		1
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0		0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0		0
Number of Available-for-sale Securities In Continuous Loss Position For 12 months or Greater	0		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	15		15
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	2		2
Number of Available-for-sale Securities In Continuous Loss Position Aggregate	1		1
Preferred Stock [Member]
Unrealized Gain (Loss) on Investments [Abstract]
Available-for-sale Equity Securities, Amortized Cost Basis	569		760
Available-for-sale Securities, Gross Unrealized Gains	362		365
Available-for-sale Securities, Gross Unrealized Losses	0		0
Available-for-sale Securities, Fair Value	931		1,125
Equity Securities [Member]
Unrealized Gain (Loss) on Investments [Abstract]
Available-for-sale Equity Securities, Amortized Cost Basis	52,553		52,744
Available-for-sale Securities, Gross Unrealized Gains	1,663		1,156
Available-for-sale Securities, Gross Unrealized Losses	187		159
Available-for-sale Securities, Fair Value	54,029		53,741
Unrealized Continuous Losses on Investments [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	9,316		3,350
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	125		90
Number of Available-for-sale Securities In Continuous Loss Position Less Than 12 Months	3		2
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	2,938		3,931
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	62		69
Number of Available-for-sale Securities In Continuous Loss Position For 12 months or Greater	2		3
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	12,254		7,281
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	187		159
Number of Available-for-sale Securities In Continuous Loss Position Aggregate	5		5
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Available-for-sale Securities, Gross Realized Gains	0	0
Available-for-sale Securities, Gross Realized Losses	$ 0	$ 0
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Schedule of Fixed Maturities [Abstract]
Percent of residential mortgage backed to securities	92.30%