Investments (Mortgage Loans by Maturity Date) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Mortgage Loans on Real Estate [Line Items]
Mortgage loans, gross of valuation allowances	$ 2,565,492	$ 2,496,786
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	100.00%	100.00%
Due within five years
Mortgage Loans on Real Estate [Line Items]
Mortgage loans, gross of valuation allowances	899,909	987,109
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	35.10%	39.50%
Due after five years through ten years
Mortgage Loans on Real Estate [Line Items]
Mortgage loans, gross of valuation allowances	1,088,987	984,289
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	42.40%	39.40%
Due after ten years
Mortgage Loans on Real Estate [Line Items]
Mortgage loans, gross of valuation allowances	$ 576,596	$ 525,388
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	22.50%	21.10%