Investments (Mortgage Loans by Credit Quality Indicator) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Credit Quality Indicators [Line Items]
Mortgage loans, gross of valuation allowances	$ 2,534,694	$ 2,496,786
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	100.00%	100.00%
High investment grade
Credit Quality Indicators [Line Items]
Mortgage loans, gross of valuation allowances	1,266,653	1,437,244
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	50.00%	57.50%
Investment grade
Credit Quality Indicators [Line Items]
Mortgage loans, gross of valuation allowances	1,023,250	827,993
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	40.40%	33.20%
Average
Credit Quality Indicators [Line Items]
Mortgage loans, gross of valuation allowances	183,250	155,914
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	7.20%	6.20%
Watch list
Credit Quality Indicators [Line Items]
Mortgage loans, gross of valuation allowances	32,936	49,404
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	1.30%	2.00%
In or near default
Credit Quality Indicators [Line Items]
Mortgage loans, gross of valuation allowances	$ 28,605	$ 26,231
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	1.10%	1.10%