1% Convertible Senior Notes (Narrative) (Details) (USD $)	1 Months Ended		2 Months Ended	12 Months Ended
	Jan. 31, 2004	Dec. 31, 2003	Jan. 31, 2004	Dec. 31, 2011	Dec. 31, 2010 years	Dec. 31, 2009
1% Convertible Senior Notes [Abstract]
Aggregate principal amount issued of 1% convertible senior notes	$ 200,000,000	$ 200,000,000	$ 200,000,000
Interest rate of convertible note 1.00%					1.00%
Maturity Date					Dec. 15, 2033
Aggregate proceeds from issuance of 1% convertible senior notes			194,100,000
Total deferred financing costs related to the 1% convertible senior notes	5,900,000	5,900,000	5,900,000
Initial conversion price of 1% convertible senior notes (price per share)	$ 15.45	$ 15.45
Number of common stock shares equivalent per $1,000 principal amount of 1% convertible senior notes	64.7249	62.7249	64.7249
Number of common stock shares issued in connection with conversion of 1% convertible senior notes					12,929,095
Value of 1% convertible senior notes converted during the period					199,800,000
Period deferred financing costs of convertible senior notes are amortized (in years)					7
Amortization of deferred financing costs				$ 0	$ 507,000	$ 840,000