Summary Of Significant Accounting Policies (Change In Fair Value Of The Equity Index Put Option Contracts) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Option Indexed to Issuer's Equity [Line Items]
Net derivative gain (loss)	$ (11,261)	$ (1,119)	$ 3,204
Derivatives Not Designated As Hedging Instruments [Member] | Equity Index Put Option Contracts [Member]
Option Indexed to Issuer's Equity [Line Items]
Net derivative gain (loss)	$ (11,261)	$ (1,119)	$ 3,204