Equity - Exercise Price Ranges (Details)	12 Months Ended
	Dec. 31, 2016 $ / shares shares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of outstanding options (in shares) | shares	12,552,608
Outstanding options, weighted average remaining contractual term	5 years 4 months 24 days
Outstanding options, weighted average exercise price (in dollars per share)	$ 3.61
Number of exercisable options (in shares) | shares	11,680,455
Exercisable options, weighted average exercise price (in dollars per share)	$ 3.33
$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	2 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	4,385,570
Outstanding options, weighted average remaining contractual term	4 years 8 months 12 days
Outstanding options, weighted average exercise price (in dollars per share)	$ 1.19
Number of exercisable options (in shares) | shares	4,385,570
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	1,362,424
Outstanding options, weighted average remaining contractual term	4 years 1 month 6 days
Outstanding options, weighted average exercise price (in dollars per share)	$ 1.92
Number of exercisable options (in shares) | shares	1,362,424
Exercisable options, weighted average exercise price (in dollars per share)	$ 1.92
$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	878,680
Outstanding options, weighted average remaining contractual term	5 years 9 months 18 days
Outstanding options, weighted average exercise price (in dollars per share)	$ 3.06
Number of exercisable options (in shares) | shares	878,680
Exercisable options, weighted average exercise price (in dollars per share)	$ 3.06
$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	3,056,069
Outstanding options, weighted average remaining contractual term	6 years 2 months 12 days
Outstanding options, weighted average exercise price (in dollars per share)	$ 5.36
Number of exercisable options (in shares) | shares	2,937,038
Exercisable options, weighted average exercise price (in dollars per share)	$ 5.34
$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	2,324,103
Outstanding options, weighted average remaining contractual term	7 years
Outstanding options, weighted average exercise price (in dollars per share)	$ 7.30
Number of exercisable options (in shares) | shares	1,610,485
Exercisable options, weighted average exercise price (in dollars per share)	$ 7.25
$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	104,333
Outstanding options, weighted average remaining contractual term	7 years 8 months 12 days
Outstanding options, weighted average exercise price (in dollars per share)	$ 10.42
Number of exercisable options (in shares) | shares	64,829
Exercisable options, weighted average exercise price (in dollars per share)	$ 10.46