Acquisition (Revenue And Net Income Of AIS And The Company) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Business Acquisition [Line Items]
Revenues									$ 2,777,285		$ 2,775,885		$ 3,121,493
Net income	79,469	(3,782)	57,251	58,226	(23,647)	96,849	17,817	61,179	191,164		152,198		403,072
Parent Company [Member]
Business Acquisition [Line Items]
Revenues									(455)		2,371		7,500
Net income									191,164		152,198		403,072
Combined Entity [Member]
Business Acquisition [Line Items]
Revenues									2,777,285	[1]	2,775,885	[1]	3,121,493	[1]
Net income									191,164		152,198		403,072
AIS [Member] | AIS [Member]
Business Acquisition [Line Items]
Revenues									13,742	[2]	13,926	[2]	11,846	[2]
Net income									$ 2,617	[2]	$ 3,367	[2]	$ 1,228	[2]

[1] Includes net premiums earned, net investment income, net realized investment gains, and commission revenues.

[2] Excludes intercompany transactions with the Company's insurance subsidiaries.