Reinsurance (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Life Insurance in Force, Gross Amount	$ 15,800,701us-gaap_LifeInsuranceInForceGross	$ 15,102,466us-gaap_LifeInsuranceInForceGross	$ 14,632,272us-gaap_LifeInsuranceInForceGross
Life Insurance in Force, Ceded to Other Companies	3,360,016us-gaap_LifeInsuranceInForceCeded	3,231,421us-gaap_LifeInsuranceInForceCeded	3,070,951us-gaap_LifeInsuranceInForceCeded
Life Insurance in Force, Assumed from Other Companies	0us-gaap_LifeInsuranceInForceAssumed	0us-gaap_LifeInsuranceInForceAssumed	0us-gaap_LifeInsuranceInForceAssumed
Life Insurance in Force, Net Amount	12,440,685us-gaap_LifeInsuranceInForceNet	11,871,045us-gaap_LifeInsuranceInForceNet	11,561,321us-gaap_LifeInsuranceInForceNet
Life Insurance in Force, Percentage of Amount Assumed to Net	0.00%	0.00%	0.00%
Premiums
Gross Amount	739,281us-gaap_DirectPremiumsEarned	717,494us-gaap_DirectPremiumsEarned	696,721us-gaap_DirectPremiumsEarned
Ceded to Other Companies	27,276us-gaap_CededPremiumsEarned	29,990us-gaap_CededPremiumsEarned	29,634us-gaap_CededPremiumsEarned
Assumed from Other Companies	3,755us-gaap_AssumedPremiumsEarned	3,434us-gaap_AssumedPremiumsEarned	3,440us-gaap_AssumedPremiumsEarned
Net Amount	715,760us-gaap_PremiumsEarnedNet	690,938us-gaap_PremiumsEarnedNet	670,527us-gaap_PremiumsEarnedNet
Percentage of Amount Assumed to Net	0.50%us-gaap_PremiumsPercentageAssumedToNet	0.50%us-gaap_PremiumsPercentageAssumedToNet	0.50%us-gaap_PremiumsPercentageAssumedToNet
Property And Casualty Segment [Member]
Premiums
Gross Amount	599,230	582,780	566,853
Ceded to Other Companies	21,157	24,260	23,954
Assumed from Other Companies	3,755	3,434	3,440
Net Amount	581,828	561,954	546,339
Percentage of Amount Assumed to Net	0.60%	0.60%	0.60%
Annuity [Member]
Premiums
Gross Amount	25,540	22,575	21,794
Ceded to Other Companies	0	0	0
Assumed from Other Companies	0	0	0
Net Amount	25,540	22,575	21,794
Percentage of Amount Assumed to Net	0.00%	0.00%	0.00%
Life [Member]
Premiums
Gross Amount	114,511	112,139	108,074
Ceded to Other Companies	6,119	5,730	5,680
Assumed from Other Companies	0	0	0
Net Amount	$ 108,392	$ 106,409	$ 102,394
Percentage of Amount Assumed to Net	0.00%	0.00%	0.00%

Amount of earned premiums assumed from other entities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 17

-Article 12

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 235

-Section S99

-Paragraph 2

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-URI http://asc.fasb.org/extlink&oid=34713774&loc=d3e574992-122915

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 225

-Section S99

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-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 17

-Article 12

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 235

-Section S99

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-Subparagraph (SX 210.12-17)

-URI http://asc.fasb.org/extlink&oid=34713774&loc=d3e574992-122915

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 225

-Section S99

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-Subparagraph (SX 210.7-04.1)

-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

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Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-Section 50

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Amount of life insurance issued and outstanding assumed from other entities. Includes, but not limited to, dividends and adjustments to face value.

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Amount before contracts ceded to other entities and contracts assumed by the entity of life insurance issued and outstanding. Includes, but not limited to, dividends and adjustments to face value.

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Amount after contracts ceded to other entities and contracts assumed by the entity of life insurance issued and outstanding. Includes, but not limited to, dividends and adjustments to face value.

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Percentage of assumed life insurance issued and outstanding contracts to life insurance issued and outstanding after contracts ceded to other entities and contracts assumed by the entity. Includes, but not limited to, dividends and adjustments to face value.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 17

-Article 12

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 235

-Section S99

-Paragraph 2

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-URI http://asc.fasb.org/extlink&oid=34713774&loc=d3e574992-122915

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-04.1)

-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 1

-Article 7

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 605

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547

Reference 6: http://www.xbrl.org/2003/role/presentationRef

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