Reinsurance (Schedule Of Rating For Existing Reinsurance) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Best Ratings of Reinsurer [Line Items]
Best Ratings of Reinsurer	$ 5,421,697
Less: Allowance	(10,633)	(15,635)
Net reinsurance recoverable	5,411,064	4,997,316
A++ Or A+ [Member]
Best Ratings of Reinsurer [Line Items]
Best Ratings of Reinsurer	2,535,134
A Or A- [Member]
Best Ratings of Reinsurer [Line Items]
Best Ratings of Reinsurer	1,716,917
B++ Or B+ [Member]
Best Ratings of Reinsurer [Line Items]
Best Ratings of Reinsurer	64,643
Not Rated [Member]
Best Ratings of Reinsurer [Line Items]
Best Ratings of Reinsurer	1,105,003
Ceded Future Policyholder Benefits And Expense [Member]
Best Ratings of Reinsurer [Line Items]
Best Ratings of Reinsurer	3,399,938
Less: Allowance	0
Net reinsurance recoverable	3,399,938
Ceded Future Policyholder Benefits And Expense [Member] | A++ Or A+ [Member]
Best Ratings of Reinsurer [Line Items]
Best Ratings of Reinsurer	1,843,575
Ceded Future Policyholder Benefits And Expense [Member] | A Or A- [Member]
Best Ratings of Reinsurer [Line Items]
Best Ratings of Reinsurer	1,514,287
Ceded Future Policyholder Benefits And Expense [Member] | B++ Or B+ [Member]
Best Ratings of Reinsurer [Line Items]
Best Ratings of Reinsurer	40,209
Ceded Future Policyholder Benefits And Expense [Member] | Not Rated [Member]
Best Ratings of Reinsurer [Line Items]
Best Ratings of Reinsurer	1,867
Ceded Unearned Premiums [Member]
Best Ratings of Reinsurer [Line Items]
Best Ratings of Reinsurer	1,013,778
Less: Allowance	0
Net reinsurance recoverable	1,013,778
Ceded Unearned Premiums [Member] | A++ Or A+ [Member]
Best Ratings of Reinsurer [Line Items]
Best Ratings of Reinsurer	40,389
Ceded Unearned Premiums [Member] | A Or A- [Member]
Best Ratings of Reinsurer [Line Items]
Best Ratings of Reinsurer	60,693
Ceded Unearned Premiums [Member] | B++ Or B+ [Member]
Best Ratings of Reinsurer [Line Items]
Best Ratings of Reinsurer	20,132
Ceded Unearned Premiums [Member] | Not Rated [Member]
Best Ratings of Reinsurer [Line Items]
Best Ratings of Reinsurer	892,564
Ceded Claims And Benefits Payable [Member]
Best Ratings of Reinsurer [Line Items]
Best Ratings of Reinsurer	945,900
Less: Allowance	0
Net reinsurance recoverable	945,900
Ceded Claims And Benefits Payable [Member] | A++ Or A+ [Member]
Best Ratings of Reinsurer [Line Items]
Best Ratings of Reinsurer	642,282
Ceded Claims And Benefits Payable [Member] | A Or A- [Member]
Best Ratings of Reinsurer [Line Items]
Best Ratings of Reinsurer	136,162
Ceded Claims And Benefits Payable [Member] | B++ Or B+ [Member]
Best Ratings of Reinsurer [Line Items]
Best Ratings of Reinsurer	4,297
Ceded Claims And Benefits Payable [Member] | Not Rated [Member]
Best Ratings of Reinsurer [Line Items]
Best Ratings of Reinsurer	163,159
Ceded Paid Losses [Member]
Best Ratings of Reinsurer [Line Items]
Best Ratings of Reinsurer	62,081
Less: Allowance	(10,633)
Net reinsurance recoverable	51,448
Ceded Paid Losses [Member] | A++ Or A+ [Member]
Best Ratings of Reinsurer [Line Items]
Best Ratings of Reinsurer	8,888
Ceded Paid Losses [Member] | A Or A- [Member]
Best Ratings of Reinsurer [Line Items]
Best Ratings of Reinsurer	5,775
Ceded Paid Losses [Member] | B++ Or B+ [Member]
Best Ratings of Reinsurer [Line Items]
Best Ratings of Reinsurer	5
Ceded Paid Losses [Member] | Not Rated [Member]
Best Ratings of Reinsurer [Line Items]
Best Ratings of Reinsurer	$ 47,413