Stock-Based Compensation and Stockholders' Equity (Net Capital Deficiency) (Details 3) (USD $)	9 Months Ended		3 Months Ended		9 Months Ended												1 Months Ended	3 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 Stock options	Sep. 30, 2011 Stock options	Sep. 30, 2012 Stock options	Sep. 30, 2011 Stock options	Sep. 30, 2012 Stock options Minimum	Sep. 30, 2011 Stock options Minimum	Sep. 30, 2012 Stock options Maximum	Sep. 30, 2011 Stock options Maximum	Sep. 30, 2012 Stock options 2004 and 2012 Plans	Sep. 30, 2011 Stock options 2004 and 2012 Plans	Sep. 30, 2012 RSUs 2004 and 2012 Plans Time-Based	Sep. 30, 2011 RSUs 2004 and 2012 Plans Time-Based	Sep. 30, 2012 RSAs 2004 and 2012 Plans Time-Based	Sep. 30, 2011 RSAs 2004 and 2012 Plans Time-Based	Feb. 29, 2012 RSAs 2004 and 2012 Plans Performance-Contingent	Sep. 30, 2012 RSAs 2004 and 2012 Plans Performance-Contingent item	Sep. 30, 2012 RSAs 2004 and 2012 Plans Performance-Contingent item	Sep. 30, 2011 RSAs 2004 and 2012 Plans Performance-Contingent	Dec. 31, 2011 RSAs 2004 and 2012 Plans Performance-Contingent
Compensation Awards
Number of Compensation Awards Granted (in shares)											269,000	582,250
Number of Compensation Awards Granted (in shares)													528,381	465,000	402,500	1,168,000	44,500		44,500	1,315,000	1,290,000
Weighted-Average Exercise Price (in dollars per share)											$ 21.83	$ 22.06
Weighted-Average Fair Value (in dollars per share)													$ 18.45	$ 25.03	$ 18.11	$ 24.59			$ 18.11	$ 24.26
Number of possible performance conditions, achievement of which not probable																		1	1
Number of possible performance conditions																		3	3
Compensation expense	$ 18,044,000	$ 18,706,000																$ 300,000
Weighted-average assumptions
Risk-free interest rate, minimum (as a percent)			0.83%	1.20%	0.74%	1.20%
Risk-free interest rate, maximum (as a percent)			0.86%	2.17%	1.17%	2.57%
Expected life			6 years	6 years			5 years	5 years	6 years	6 years
Volatility (as a percent)			57.00%	53.00%			55.00%	49.00%	60.00%	55.00%
Weighted-average estimated fair value of ESPP issuances (in dollars per share)			$ 14.31	$ 9.74	$ 11.41	$ 11.15
Stockholders' equity (net capital deficiency):
Options exercised					882,666
Shares exercised, Weighted-Average Exercise Price of Outstanding Options (in dollars per share)					$ 8.28
Total cash proceed					$ 7,300,000