Debt (Components Of Convertible Senior Notes) (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Apr. 06, 2009
Debt [Abstract]
Debt principal			$ 190,000,000
Contractual interest expense on the coupon	8,550,000	8,550,000
Amortization of the discount component and debt issue fees recognized as interest expense	12,853,000	11,319,000
Total interest expense on the convertible debt	$ 21,403,000	$ 19,869,000