Equity Exercise Price Ranges (Details)	12 Months Ended
	Dec. 31, 2015 $ / shares shares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of outstanding options (in shares) | shares	14,019,629
Outstanding options, weighted average remaining contractual term	6 years 6 months
Outstanding options, weighted average exercise price (in dollars per share)	$ 3.62
Number of exercisable options (in shares) | shares	10,951,694
Exercisable options, weighted average exercise price (in dollars per share)	$ 2.80
$0.50 - $0.76
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower range limit (in dollars per share)	0.50
Exercise price range, upper range limit (in dollars per share)	$ 0.76
Number of outstanding options (in shares) | shares	441,429
Outstanding options, weighted average remaining contractual term	3 years 4 months 24 days
Outstanding options, weighted average exercise price (in dollars per share)	$ 0.72
Number of exercisable options (in shares) | shares	441,429
Exercisable options, weighted average exercise price (in dollars per share)	$ 0.72
$0.87 - $1.35
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower range limit (in dollars per share)	0.87
Exercise price range, upper range limit (in dollars per share)	$ 1.35
Number of outstanding options (in shares) | shares	4,783,304
Outstanding options, weighted average remaining contractual term	5 years 8 months 12 days
Outstanding options, weighted average exercise price (in dollars per share)	$ 1.19
Number of exercisable options (in shares) | shares	4,783,304
Exercisable options, weighted average exercise price (in dollars per share)	$ 1.19
$1.40 - $2.45
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower range limit (in dollars per share)	1.40
Exercise price range, upper range limit (in dollars per share)	$ 2.45
Number of outstanding options (in shares) | shares	1,641,928
Outstanding options, weighted average remaining contractual term	5 years 1 month 6 days
Outstanding options, weighted average exercise price (in dollars per share)	$ 1.93
Number of exercisable options (in shares) | shares	1,641,928
Exercisable options, weighted average exercise price (in dollars per share)	$ 1.93
$2.66 - $3.99
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower range limit (in dollars per share)	2.66
Exercise price range, upper range limit (in dollars per share)	$ 3.99
Number of outstanding options (in shares) | shares	957,454
Outstanding options, weighted average remaining contractual term	6 years 9 months 18 days
Outstanding options, weighted average exercise price (in dollars per share)	$ 3.05
Number of exercisable options (in shares) | shares	907,452
Exercisable options, weighted average exercise price (in dollars per share)	$ 3.00
$4.19 - $6.38
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower range limit (in dollars per share)	4.19
Exercise price range, upper range limit (in dollars per share)	$ 6.38
Number of outstanding options (in shares) | shares	3,552,323
Outstanding options, weighted average remaining contractual term	7 years 4 months 24 days
Outstanding options, weighted average exercise price (in dollars per share)	$ 5.35
Number of exercisable options (in shares) | shares	2,229,386
Exercisable options, weighted average exercise price (in dollars per share)	$ 5.32
$6.45- $9.78
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower range limit (in dollars per share)	6.45
Exercise price range, upper range limit (in dollars per share)	$ 9.78
Number of outstanding options (in shares) | shares	2,527,525
Outstanding options, weighted average remaining contractual term	8 years 1 month 6 days
Outstanding options, weighted average exercise price (in dollars per share)	$ 7.29
Number of exercisable options (in shares) | shares	914,703
Exercisable options, weighted average exercise price (in dollars per share)	$ 7.18
$9.90 - $10.99
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower range limit (in dollars per share)	9.90
Exercise price range, upper range limit (in dollars per share)	$ 10.99
Number of outstanding options (in shares) | shares	115,666
Outstanding options, weighted average remaining contractual term	8 years 10 months 24 days
Outstanding options, weighted average exercise price (in dollars per share)	$ 10.43
Number of exercisable options (in shares) | shares	33,492
Exercisable options, weighted average exercise price (in dollars per share)	$ 10.50