Stock-Based Compensation Plans (Narrative) (Details) (USD $)	12 Months Ended							12 Months Ended		12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2011 Employee Stock Option Plan [Member] years	Dec. 31, 2011 Non-Employee Director Stock Option Plan [Member]	Dec. 31, 2011 Employee Stock Purchase Plan [Member]	Dec. 31, 2003 Employee Stock Purchase Plan [Member]	Dec. 31, 2011 Restricted Stock Plan [Member] years	Dec. 31, 2008 Restricted Stock Plan [Member]	Dec. 31, 2011 Minimum [Member] Employee Stock Option Plan [Member]	Dec. 31, 2011 Minimum [Member] Restricted Stock Plan [Member]	Dec. 31, 2010 Minimum [Member] Restricted Stock Plan [Member]	Dec. 31, 2009 Minimum [Member] Restricted Stock Plan [Member]	Dec. 31, 2011 Maximum [Member] Employee Stock Option Plan [Member]	Dec. 31, 2011 Maximum [Member] Restricted Stock Plan [Member]	Dec. 31, 2010 Maximum [Member] Restricted Stock Plan [Member]	Dec. 31, 2009 Maximum [Member] Restricted Stock Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options available for grant				18,000,000
Options granted net of shares from canceled/expired options				11,371,704	549,240
Option vesting period					six					one				five
Option expiration period, years					10
Option expiration period, years										three				seven
Unrecognized compensation cost				$ 21,155,605
Weighted-average period for unrecognized compensation cost expected to be recognized				2.2
Shares approved					1,000,000		1,200,000		2,000,000
Shares sold to employees during period	68,630	81,249	121,346			964,928
ESPP discount rate						85.00%
Weighted average fair value of shares sold						$ 24.17
Shares granted with restriction period	140,900	117,050	186,080					590,920
Restricted period, maximum, in years								10
Restricted period for granted shares, in years								5
Market price											$ 24.96	$ 17.98	$ 9.96		$ 30.25	$ 29.46	$ 18.03
Unearned stock-based compensation								7,102,402
Amortization expense								$ 2,039,377