Earnings Per Common Share (Narrative) (Details)									3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended
	Sep. 30, 2011	Dec. 31, 2010	Sep. 30, 2011 3.75% Convertible Notes Due October 22, 2012 [Member]	Dec. 31, 2010 3.75% Convertible Notes Due October 22, 2012 [Member]	Sep. 30, 2011 3.75% Convertible Notes Due October 22, 2012 [Member] Convertible Debt Securities [Member]	Sep. 30, 2011 2.50% Convertible Senior Notes Due August 15, 2013 [Member]	Feb. 28, 2010 2.50% Convertible Senior Notes Due August 15, 2013 [Member]	Mar. 31, 2008 2.50% Convertible Senior Notes Due August 15, 2013 [Member]	Sep. 30, 2011 Restricted Stock And PSU [Member]	Sep. 30, 2010 Restricted Stock And PSU [Member]	Sep. 30, 2011 Restricted Stock And PSU [Member]	Sep. 30, 2010 Restricted Stock And PSU [Member]	Sep. 30, 2011 Common Stock [Member]	Sep. 30, 2010 Common Stock [Member]	Sep. 30, 2011 Common Stock [Member]	Sep. 30, 2010 Common Stock [Member]	Sep. 30, 2011 Convertible Common Stock [Member]	Sep. 30, 2010 Convertible Common Stock [Member]
Earnings Per Share Basic And Diluted [Line Items]
Stock options to purchase shares	10,073,893	10,112,842							4,954,820	4,219,424	4,954,820	4,219,424	10,073,893	10,467,993	10,073,893	10,467,993
Incremental common shares attributable to conversion of debt securities																	34,482	34,482
Weighted Average Number Diluted Shares Outstanding Adjustment									4,871,857	3,196,888	3,012,499	1,479,215	6,582,278	5,170,077	6,623,764	5,170,077
Debt instrument, interest rate, stated percentage			3.75%	3.75%	3.75%	2.50%	2.50%	2.50%