Investments (Commercial Mortgage and Other Loans) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
Sep. 30, 2012	Dec. 31, 2011
Commercial mortgage loans	$ 404,862	$ 397,291
Commercial mortgage loans, Percentage	87.40%	88.10%
Valuation allowance	(2,088)	(1,501)
Total net commercial and agricultural mortgage loans by property type	463,274	450,860
Total commercial mortgage and other loans	461,186	449,359
Office buildings [Member]
Commercial mortgage loans	59,684	60,220
Commercial mortgage loans, Percentage	12.90%	13.30%
Retail stores [Member]
Commercial mortgage loans	80,490	68,369
Commercial mortgage loans, Percentage	17.40%	15.10%
Apartment Complexes [Member]
Commercial mortgage loans	111,297	114,900
Commercial mortgage loans, Percentage	24.00%	25.50%
Industrial Buildings [Member]
Commercial mortgage loans	144,163	144,513
Commercial mortgage loans, Percentage	31.10%	32.10%
Agricultural Properties [Member]
Commercial mortgage loans	53,815	48,964
Commercial mortgage loans, Percentage	11.60%	10.90%
Hospitality [Member]
Commercial mortgage loans	9,228	9,289
Commercial mortgage loans, Percentage	2.00%	2.10%
Other [Member]
Commercial mortgage loans	$ 4,597	$ 4,605
Commercial mortgage loans, Percentage	1.00%	1.00%
California [Member]
Commercial mortgage loans, Percentage	23.00%
Ohio [Member]
Commercial mortgage loans, Percentage	10.00%
New York [Member]
Commercial mortgage loans, Percentage	16.00%

The allowance for commercial loan and lease losses represents the reserve to cover probable credit losses related to specifically identified commercial loans and leases, as well as probable credit losses inherent in the remainder of the commercial loan portfolio as of the balance sheet date. For banks, include currently required allocated transfer risk reserves. Include carryover of or adjustments to the allowance for commercial loan losses in connection with business combinations determined to be appropriate.

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-LegacyDoc This is a non-GAAP reference that was included in the 2009 taxonomy. It will be removed from future versions of this taxonomy.

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

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

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-Name Statement of Financial Accounting Standard (FAS)

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-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

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-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 10: http://www.xbrl.org/2003/role/presentationRef

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Reference 11: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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-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.

+ Details

- Definition

Amount before allowance of mortgage loans on existing land or building. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans covered under loss sharing agreements.

+ References+ Details