Investments (Mortgage Loans by Property Type) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Mortgage Loans on Real Estate [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 3,136,764	$ 2,718,709
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	100.00%	100.00%
Office Building [Member]
Mortgage Loans on Real Estate [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 980,858	$ 851,749
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	31.30%	31.30%
Retail Site [Member]
Mortgage Loans on Real Estate [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 1,026,018	$ 802,466
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	32.70%	29.60%
Industrial Property [Member]
Mortgage Loans on Real Estate [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 527,485	$ 466,583
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	16.80%	17.20%
Apartment Building [Member]
Mortgage Loans on Real Estate [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 420,014	$ 376,430
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	13.40%	13.80%
Other Property [Member]
Mortgage Loans on Real Estate [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 182,389	$ 221,481
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	5.80%	8.10%