Stock Option and Purchase Plans (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2013
Range of Exercise Prices $3.13 - $10.19
Summary of Stock Options
Exercise price, low end of the range (in dollars per share)	$ 3.13
Exercise price, high end of the range (in dollars per share)	$ 10.19
Options Outstanding
Number Outstanding at end of the period (in shares)	3,318,235
Weighted-Average Remaining Contractual Life	3 years 4 months 24 days
Weighted-Average Exercise Price (in dollars per share)	$ 7.23
Options Exercisable
Number Exercisable at the end of the period (in shares)	3,296,690
Weighted Average Exercise Price (in dollars per share)	$ 7.22
Range of Exercise Prices $12.04 - $12.84
Summary of Stock Options
Exercise price, low end of the range (in dollars per share)	$ 12.04
Exercise price, high end of the range (in dollars per share)	$ 12.84
Options Outstanding
Number Outstanding at end of the period (in shares)	3,215,931
Weighted-Average Remaining Contractual Life	5 years 2 months 12 days
Weighted-Average Exercise Price (in dollars per share)	$ 12.29
Options Exercisable
Number Exercisable at the end of the period (in shares)	2,466,649
Weighted Average Exercise Price (in dollars per share)	$ 12.22
Range of Exercise Prices $12.90 - $25.74
Summary of Stock Options
Exercise price, low end of the range (in dollars per share)	$ 12.90
Exercise price, high end of the range (in dollars per share)	$ 25.74
Options Outstanding
Number Outstanding at end of the period (in shares)	2,372,285
Weighted-Average Remaining Contractual Life	7 years 1 month 6 days
Weighted-Average Exercise Price (in dollars per share)	$ 18.52
Options Exercisable
Number Exercisable at the end of the period (in shares)	853,216
Weighted Average Exercise Price (in dollars per share)	$ 22.08
Range of Exercise Prices $3.13 - $25.74
Summary of Stock Options
Exercise price, low end of the range (in dollars per share)	$ 3.13
Exercise price, high end of the range (in dollars per share)	$ 25.74
Options Outstanding
Number Outstanding at end of the period (in shares)	8,906,451
Weighted-Average Remaining Contractual Life	5 years 1 month 6 days
Weighted-Average Exercise Price (in dollars per share)	$ 12.06
Options Exercisable
Number Exercisable at the end of the period (in shares)	6,616,555
Weighted Average Exercise Price (in dollars per share)	$ 11.00