Reinsurance (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2011 Statements Entities Y RatingCategories Counterparties Securities Agreements Policies D Subsidiaries Markets Companies FiscalQuarters Transactions	Jun. 30, 2010	Jun. 30, 2011 RatingAgency RatingCategories Subsidiaries Counterparties Securities Agreements Policies D Markets Companies FiscalQuarters Entities Transactions	Jun. 30, 2010
Reinsurance
Reduction to net income if unearned assumed premiums are recaptured	$ 23,100,000		$ 23,100,000
Number of Ceding Company	1		1
Reduction to net income if additional unearned assumed premiums are recaptured	12,400,000		12,400,000
Commutation gains (losses)	8,100,000	2,200,000	32,200,000	16,700,000
Increase (Decrease) in Net Unearned Premium Reserve	(22,400,000)	6,200,000	(20,100,000)	60,400,000
Increase (Decrease) in Net Par	(1,045,000,000)	537,000,000	(780,000,000)	8,374,000,000
Premiums Written:
Direct	26,900,000	102,000,000	57,400,000	195,700,000
Assumed	(9,900,000)	(10,100,000)	(51,900,000)	(11,800,000)
Ceded (1)	400,000	6,500,000	4,400,000	58,100,000
Net	17,400,000	98,400,000	9,900,000	242,000,000
Premiums Earned:
Direct	238,600,000	309,400,000	514,900,000	636,100,000
Assumed	21,000,000	17,900,000	31,000,000	36,900,000
Ceded	(29,600,000)	(30,300,000)	(61,900,000)	(61,300,000)
Net	230,068,000	297,050,000	484,045,000	611,670,000
Loss and LAE:
Direct	129,400,000	77,300,000	136,500,000	220,200,000
Assumed	7,200,000	12,400,000	(5,800,000)	40,500,000
Ceded	(12,700,000)	(4,000,000)	(32,300,000)	(64,100,000)
Net	$ 123,913,000	$ 85,770,000	$ 98,333,000	$ 196,622,000