Reinsurance (Details) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2011 Entities RatingCategories Y Statements Securities Policies D Companies Agreements Markets Subsidiaries Transactions FiscalQuarters Counterparties	Jun. 30, 2010	Jun. 30, 2011 RatingCategories Subsidiaries Securities Policies D Companies Agreements Markets Transactions FiscalQuarters Counterparties Entities	Jun. 30, 2010	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
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	101,900,000	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	98,300,000	9,900,000	242,000,000
Premiums Earned:
Direct	238,600,000	304,500,000	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	292,110,000	484,045,000	611,670,000	1,186,700,000	930,400,000	261,400,000
Loss and LAE:
Direct	138,400,000	62,800,000	144,000,000	226,100,000
Assumed	7,200,000	12,400,000	(5,800,000)	40,500,000
Ceded	(12,700,000)	(4,000,000)	(32,300,000)	(64,900,000)
Net	$ 132,908,000	$ 71,156,000	$ 105,861,000	$ 201,657,000	$ 413,800,000	$ 377,800,000	$ 265,800,000