Common Stock (Narrative) (Details) (USD $)	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 Employee Stock Option [Member]	Dec. 31, 2010 Employee Stock Option [Member]	Dec. 31, 2011 QUIPS [Member]	Dec. 31, 2010 QUIPS [Member]	Dec. 31, 2011 Convertible subordinated notes - 1 7/8 percent	Dec. 31, 2010 Convertible subordinated notes - 1 7/8 percent	Dec. 31, 2011 Convertible Subordinated Notes Four Percent [Member]	Dec. 31, 2010 Convertible Subordinated Notes Four Percent [Member]	Dec. 31, 2011 Convertible Subordinated Notes Four Percent [Member]	Nov. 30, 2009 Convertible Subordinated Notes Four Percent [Member]	Dec. 31, 2011 1 7/8 percent Convertible Senior Subordinated Notes
Class of Stock [Line Items]
Common Stock, Shares Authorized (in shares)	500,000,000	500,000,000
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Stock, Capital Shares Reserved for Future Issuance (in shares)			1,500,000	3,400,000	1,300,000	3,000,000	1,000,000	1,000,000	18,900,000	19,400,000
Debt Instrument, Interest Rate, Stated Percentage											4.00%	4.00%	1.875%
Debt Instrument, Convertible, Conversion Price (in dollars per share)											$ 11.11		$ 29.55
Share-based Compensation, Not Yet Vested (in shares)	1,000,000
Share-based Compensation Arrangement, Number of Shares Available for Grant (in shares)	1,700,000