Investments (Details 7) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2011	Dec. 31, 2010
Gross unrealized losses with number of securities [Line Items]
Available For Sale Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions	961,000	1,028,000
Available For Sale Securities Gross Unrealized Losses	$ 233,819	$ 319,131
Percentage Of Total Gross Unrealized Losses For Fixed Maturity And Equity Securities	100.00%	100.00%
Less Than 20 Percent Member
Gross unrealized losses with number of securities [Line Items]
Available For Sale Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions	890,000	908,000
Available For Sale Securities Gross Unrealized Losses	123,789	146,404
Percentage Of Total Gross Unrealized Losses For Fixed Maturity And Equity Securities	52.90%	45.90%
More Than Or Equal To 20 Percent For Less Than Six Months Member
Gross unrealized losses with number of securities [Line Items]
Available For Sale Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions	15,000	14,000
Available For Sale Securities Gross Unrealized Losses	7,965	18,114
Percentage Of Total Gross Unrealized Losses For Fixed Maturity And Equity Securities	3.40%	5.70%
More Than Or Equal To 20 Percent For Six Months Or Greater Member
Gross unrealized losses with number of securities [Line Items]
Available For Sale Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions	56,000	106,000
Available For Sale Securities Gross Unrealized Losses	$ 102,065	$ 154,613
Percentage Of Total Gross Unrealized Losses For Fixed Maturity And Equity Securities	43.70%	48.40%