Investments (Details 12) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Mortgage Loans On Real Estate Geographic Location Of Property [Line Items]
Loans Receivable Commercial Real Estate	$ 2,335,115,000	$ 2,312,167,000
Pacific [Member]
Mortgage Loans On Real Estate Geographic Location Of Property [Line Items]
Loans Receivable Commercial Real Estate	597,540,000	593,589,000
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	25.60%	25.70%
South Atlantic [Member]
Mortgage Loans On Real Estate Geographic Location Of Property [Line Items]
Loans Receivable Commercial Real Estate	483,398,000	477,068,000
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	20.70%	20.50%
Mountain [Member]
Mortgage Loans On Real Estate Geographic Location Of Property [Line Items]
Loans Receivable Commercial Real Estate	251,406,000	233,174,000
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	10.80%	10.10%
Middle Atlantic [Member]
Mortgage Loans On Real Estate Geographic Location Of Property [Line Items]
Loans Receivable Commercial Real Estate	286,314,000	300,475,000
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	12.30%	13.00%
West North Central [Member]
Mortgage Loans On Real Estate Geographic Location Of Property [Line Items]
Loans Receivable Commercial Real Estate	160,203,000	168,063,000
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	6.80%	7.30%
East North Central [Member]
Mortgage Loans On Real Estate Geographic Location Of Property [Line Items]
Loans Receivable Commercial Real Estate	243,202,000	224,122,000
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	10.40%	9.70%
West South Central [Member]
Mortgage Loans On Real Estate Geographic Location Of Property [Line Items]
Loans Receivable Commercial Real Estate	160,117,000	161,451,000
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	6.90%	7.00%
East South Central [Member]
Mortgage Loans On Real Estate Geographic Location Of Property [Line Items]
Loans Receivable Commercial Real Estate	62,323,000	62,789,000
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	2.70%	2.70%
New England [Member]
Mortgage Loans On Real Estate Geographic Location Of Property [Line Items]
Loans Receivable Commercial Real Estate	$ 90,612,000	$ 91,436,000
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	3.80%	4.00%

Reflects the sum of the gross carrying amounts of unpaid loans issued to businesses to acquire, develop, construct, improve, or refinance land or a building. Includes [but is not limited to] commercial mortgage loans, which are secured by a [legal] security interest in real property [commercial building or business real property] which thereby serves as collateral securing repayment of the loan; and construction financing, which is an obligation generally in the form of a [promissory] note, used for the funding of construction projects.

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

-Publisher AICPA

-Name Audit and Accounting Guide (AAG)

-Number AAG-DEP

-Chapter 8

-Paragraph 51, 52, 53

-IssueDate 2006-05-01

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6965416&loc=d3e5066-111524

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 60

-Paragraph 47

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.7(a))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 01-6

-Paragraph 13

-Subparagraph e

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 9

-Section 03

-Paragraph 7

-Subparagraph a

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.1(c))

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details