Investments (Commercial Mortgage and Other Loans) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2016	Dec. 31, 2015
Servicing Assets at Fair Value [Line Items]
Commercial mortgage and agricultural property loans by property type:	$ 1,635,622	$ 1,652,476
Valuation allowance	(2,090)	(2,651)
Total net commercial mortgage and agricultural property loans by property type	1,633,532	1,649,825
Total other loans	8,410	8,410
Valuation allowance	0	0
Total commercial mortgage and other loans	$ 1,641,942	$ 1,658,235
% 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:	$ 1,532,136	$ 1,545,853
% of Total	93.70%	93.50%
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:	$ 387,326	$ 440,767
% of Total	23.70%	26.70%
Apartments/Multi-Family
Servicing Assets at Fair Value [Line Items]
Commercial mortgage and agricultural property loans by property type:	$ 467,242	$ 445,379
% of Total	28.60%	27.00%
Industrial
Servicing Assets at Fair Value [Line Items]
Commercial mortgage and agricultural property loans by property type:	$ 252,402	$ 254,884
% of Total	15.40%	15.40%
Office
Servicing Assets at Fair Value [Line Items]
Commercial mortgage and agricultural property loans by property type:	$ 252,435	$ 226,332
% of Total	15.40%	13.60%
Other
Servicing Assets at Fair Value [Line Items]
Commercial mortgage and agricultural property loans by property type:	$ 102,552	$ 92,581
% of Total	6.30%	5.60%
Hospitality
Servicing Assets at Fair Value [Line Items]
Commercial mortgage and agricultural property loans by property type:	$ 70,179	$ 85,910
% of Total	4.30%	5.20%
Agricultural property loans
Servicing Assets at Fair Value [Line Items]
Commercial mortgage and agricultural property loans by property type:	$ 103,486	$ 106,623
% of Total	6.30%	6.50%

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Loans Receivable, Net, Commercial, Mortgage

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Total Commercial Mortgage And Other Loans

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