Employee Stock Plans (Exercise Price Range) (Details)	12 Months Ended
	Dec. 31, 2015 $ / shares shares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number of Options Outstanding (in shares)	4,078,626
Options Exercisable, Number Exercisable (in shares)	3,000,274
$1.59 - $4.73
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit (in dollars per share) | $ / shares	$ 1.59
Exercise Price Range, Upper Range Limit (in dollars per share) | $ / shares	$ 4.73
Options Outstanding, Number of Options Outstanding (in shares)	632,802
Options Outstanding, Remaining Weighted Average Life	5 years 2 months 19 days
Options Exercisable, Number Exercisable (in shares)	527,220
Options Exercisable, Remaining Weighted Average Life	4 years 11 months 12 days
$5.14 - $7.89
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit (in dollars per share) | $ / shares	$ 5.14
Exercise Price Range, Upper Range Limit (in dollars per share) | $ / shares	$ 7.89
Options Outstanding, Number of Options Outstanding (in shares)	2,184,342
Options Outstanding, Remaining Weighted Average Life	6 years 2 months 23 days
Options Exercisable, Number Exercisable (in shares)	1,987,882
Options Exercisable, Remaining Weighted Average Life	6 years 1 month 24 days
$8.08 - $11.91
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit (in dollars per share) | $ / shares	$ 8.08
Exercise Price Range, Upper Range Limit (in dollars per share) | $ / shares	$ 11.91
Options Outstanding, Number of Options Outstanding (in shares)	983,661
Options Outstanding, Remaining Weighted Average Life	8 years 10 months 28 days
Options Exercisable, Number Exercisable (in shares)	207,351
Options Exercisable, Remaining Weighted Average Life	8 years 1 month 28 days
$13.00 - $25.89
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit (in dollars per share) | $ / shares	$ 13.00
Exercise Price Range, Upper Range Limit (in dollars per share) | $ / shares	$ 25.89
Options Outstanding, Number of Options Outstanding (in shares)	277,821
Options Outstanding, Remaining Weighted Average Life	4 years 9 months 22 days
Options Exercisable, Number Exercisable (in shares)	277,821
Options Exercisable, Remaining Weighted Average Life	4 years 9 months 22 days