Shareholders' Equity (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended		12 Months Ended				12 Months Ended				12 Months Ended
	Dec. 31, 2011	Dec. 31, 2009	Dec. 31, 2011 Accumulated Net Unrealized Investment Gain (Loss) [Member]	Dec. 31, 2010 Accumulated Net Unrealized Investment Gain (Loss) [Member]	Dec. 31, 2009 Accumulated Net Unrealized Investment Gain (Loss) [Member]	Dec. 31, 2008 Accumulated Net Unrealized Investment Gain (Loss) [Member]	Dec. 31, 2009 Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]	Dec. 31, 2010 Accumulated Translation Adjustment [Member]	Dec. 31, 2009 Accumulated Translation Adjustment [Member]	Dec. 31, 2011 Accumulated Translation Adjustment [Member]	Dec. 31, 2009 Accumulated other comprehensive income
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning Balance	$ 97,186		$ 82,673	$ 97,108		$ 11,715	$ (5,220)	$ 22,557	$ 21,041	$ 14,545
Other comprehensive income	32		130,441	(14,435)			5,220	(8,044)	1,516		89,694
Cumulative effect of accounting change (other-than temporary impairments in investments)		(4,301)			(4,301)
Accumulated Other Comprehensive Income (Loss), Net of Tax, Ending Balance	$ 227,659		$ 213,114	$ 82,673		$ 11,715		$ 14,513	$ 22,557	$ 14,545