Investments (Mortgage Loans by Maturity Date) (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%
Mortgage Loans On Real Estate Due One Year Through Five Years [Member]
Mortgage Loans on Real Estate [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 873,280	$ 860,362
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	27.80%	31.60%
Mortgage Loans On Real Estate Due After Five Years [Member]
Mortgage Loans on Real Estate [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 1,561,535	$ 1,165,530
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	49.80%	42.90%
Mortgage Loans On Real Estate Due After Ten Years [Member]
Mortgage Loans on Real Estate [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 701,949	$ 692,817
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	22.40%	25.50%