Investments (Mortgage Loans by Credit Quality Indicator) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Mortgage Loans on Real Estate [Line Items]
Mortgage loans, gross of valuation allowances	$ 2,623,933	$ 2,496,786
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	100.00%	100.00%
High investment grade
Mortgage Loans on Real Estate [Line Items]
Mortgage loans, gross of valuation allowances	1,347,805	1,437,244
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	51.40%	57.50%
Investment grade
Mortgage Loans on Real Estate [Line Items]
Mortgage loans, gross of valuation allowances	1,114,920	827,993
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	42.50%	33.20%
Average
Mortgage Loans on Real Estate [Line Items]
Mortgage loans, gross of valuation allowances	112,183	155,914
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	4.30%	6.20%
Watch list
Mortgage Loans on Real Estate [Line Items]
Mortgage loans, gross of valuation allowances	29,511	49,404
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	1.10%	2.00%
In or near default
Mortgage Loans on Real Estate [Line Items]
Mortgage loans, gross of valuation allowances	$ 19,514	$ 26,231
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	0.70%	1.10%