Investments (Summarizes The Market Value Of Those Investments In An Unrealized Loss Position For Periods Less Than And Greater Than 12 Months) (Details) (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
Schedule of Available-for-sale Securities [Line Items]
Gross Fair Value	$ 9,477	$ 50,620
Unrealized Loss	(302)	(2,594)
Non-U.S. Government And Government Agencies [Member] | Less Than 12 Months [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Fair Value		34,204
Unrealized Loss		(1,116)
States, Municipalities And Political Subdivisions [Member] | Less Than 12 Months [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Fair Value		472
Unrealized Loss		(13)
Corporate Debt, Financial Institutions [Member] | Less Than 12 Months [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Fair Value	9,477	2,796
Unrealized Loss	(302)	(38)
Corporate Debt, Industrials [Member] | Less Than 12 Months [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Fair Value		2,150
Unrealized Loss		(2)
Less Than 12 Months [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Fair Value	9,477	39,622
Unrealized Loss	(302)	(1,169)
Non-U.S. Government And Government Agencies [Member] | More Than 12 Months [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Fair Value		10,998
Unrealized Loss		(1,425)
More Than 12 Months [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Fair Value		10,998
Unrealized Loss		$ (1,425)