Investments (Commercial Mortgage and Other Loans) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2015	Dec. 31, 2014
Servicing Assets at Fair Value [Line Items]
Commercial mortgage and agricultural property loans by property type:	$ 1,704,866	$ 1,677,297
Valuation allowance	(3,799)	(4,154)
Total net commercial mortgage and agricultural property loans by property type	1,701,067	1,673,143
Total other loans	8,410	8,410
Valuation allowance	0	0
Total commercial mortgage and other loans	$ 1,709,477	$ 1,681,553
% of Total	100.00%	100.00%
Total commercial mortgage loans
Servicing Assets at Fair Value [Line Items]
Commercial mortgage and agricultural property loans by property type:	$ 1,593,875	$ 1,562,632
% of Total	93.50%	93.20%
Uncollateralized loans
Servicing Assets at Fair Value [Line Items]
Total other loans	$ 8,410	$ 8,410
Retail
Servicing Assets at Fair Value [Line Items]
Commercial mortgage and agricultural property loans by property type:	$ 443,527	$ 439,679
% of Total	26.00%	26.20%
Apartments/Multi-Family
Servicing Assets at Fair Value [Line Items]
Commercial mortgage and agricultural property loans by property type:	$ 421,133	$ 401,568
% of Total	24.70%	23.90%
Industrial
Servicing Assets at Fair Value [Line Items]
Commercial mortgage and agricultural property loans by property type:	$ 275,163	$ 286,104
% of Total	16.10%	17.10%
Office
Servicing Assets at Fair Value [Line Items]
Commercial mortgage and agricultural property loans by property type:	$ 274,751	$ 244,072
% of Total	16.10%	14.60%
Other
Servicing Assets at Fair Value [Line Items]
Commercial mortgage and agricultural property loans by property type:	$ 92,842	$ 99,083
% of Total	5.40%	5.90%
Hospitality
Servicing Assets at Fair Value [Line Items]
Commercial mortgage and agricultural property loans by property type:	$ 86,459	$ 92,126
% of Total	5.20%	5.50%
Agricultural property loans
Servicing Assets at Fair Value [Line Items]
Commercial mortgage and agricultural property loans by property type:	$ 110,991	$ 114,665
% of Total	6.50%	6.80%

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Total Commercial Mortgage And Other Loans

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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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