Stockholders' Equity - Summary of outstanding and vested stock options (Details) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of options outstanding (in shares)	2,582,517	3,027,717
Weighted average remaining contractual term, outstanding (in years)	5 years 11 months 20 days
Weighted average exercise price (in dollars per share)	$ 102.64	$ 69.53
Number of shares, options vested and exercisable (in shares)	1,776,779
Weighted average exercise price, options vested and exercisable (in dollars per share)	$ 61.55
$0.46 - $1.50
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, lower limit (in dollars per share)	0.46
Range of exercise prices, upper limit (in dollars per share)	$ 1.5
Number of options outstanding (in shares)	24,343
Weighted average remaining contractual term, outstanding (in years)	1 year 10 months 17 days
Weighted average exercise price (in dollars per share)	$ 1.13
Number of shares, options vested and exercisable (in shares)	24,343
Weighted average exercise price, options vested and exercisable (in dollars per share)	$ 1.13
$2.32
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, upper limit (in dollars per share)	$ 2.32
Number of options outstanding (in shares)	696,477
Weighted average remaining contractual term, outstanding (in years)	3 years 1 month 20 days
Weighted average exercise price (in dollars per share)	$ 2.32
Number of shares, options vested and exercisable (in shares)	696,477
Weighted average exercise price, options vested and exercisable (in dollars per share)	$ 2.32
$3.00 - $19.63
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, lower limit (in dollars per share)	3.00
Range of exercise prices, upper limit (in dollars per share)	$ 19.63
Number of options outstanding (in shares)	319,989
Weighted average remaining contractual term, outstanding (in years)	5 years 2 months 8 days
Weighted average exercise price (in dollars per share)	$ 12.94
Number of shares, options vested and exercisable (in shares)	271,076
Weighted average exercise price, options vested and exercisable (in dollars per share)	$ 12.18
$22.59 - $45.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, lower limit (in dollars per share)	22.59
Range of exercise prices, upper limit (in dollars per share)	$ 45.00
Number of options outstanding (in shares)	261,161
Weighted average remaining contractual term, outstanding (in years)	5 years 1 month 17 days
Weighted average exercise price (in dollars per share)	$ 27.10
Number of shares, options vested and exercisable (in shares)	251,095
Weighted average exercise price, options vested and exercisable (in dollars per share)	$ 27.07
$48.24 - $161.34
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, lower limit (in dollars per share)	48.24
Range of exercise prices, upper limit (in dollars per share)	$ 161.34
Number of options outstanding (in shares)	78,368
Weighted average remaining contractual term, outstanding (in years)	6 years 7 months 20 days
Weighted average exercise price (in dollars per share)	$ 93.13
Number of shares, options vested and exercisable (in shares)	38,260
Weighted average exercise price, options vested and exercisable (in dollars per share)	$ 81.15
$170.46
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, upper limit (in dollars per share)	$ 170.46
Number of options outstanding (in shares)	518,391
Weighted average remaining contractual term, outstanding (in years)	7 years 1 month 28 days
Weighted average exercise price (in dollars per share)	$ 170.46
Number of shares, options vested and exercisable (in shares)	286,728
Weighted average exercise price, options vested and exercisable (in dollars per share)	$ 170.46
$172.02- $204.04
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, lower limit (in dollars per share)	172.02
Range of exercise prices, upper limit (in dollars per share)	$ 204.04
Number of options outstanding (in shares)	320,857
Weighted average remaining contractual term, outstanding (in years)	8 years 3 months 14 days
Weighted average exercise price (in dollars per share)	$ 201.22
Number of shares, options vested and exercisable (in shares)	129,149
Weighted average exercise price, options vested and exercisable (in dollars per share)	$ 200.20
$207.33 - $240.50
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, lower limit (in dollars per share)	207.33
Range of exercise prices, upper limit (in dollars per share)	$ 240.50
Number of options outstanding (in shares)	142,677
Weighted average remaining contractual term, outstanding (in years)	8 years 11 months 5 days
Weighted average exercise price (in dollars per share)	$ 232.25
Number of shares, options vested and exercisable (in shares)	37,946
Weighted average exercise price, options vested and exercisable (in dollars per share)	$ 227.82
$267.20
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, upper limit (in dollars per share)	$ 267.20
Number of options outstanding (in shares)	216,111
Weighted average remaining contractual term, outstanding (in years)	9 years 1 month 20 days
Weighted average exercise price (in dollars per share)	$ 267.20
Number of shares, options vested and exercisable (in shares)	40,843
Weighted average exercise price, options vested and exercisable (in dollars per share)	$ 267.20
$267.92
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, upper limit (in dollars per share)	$ 267.92
Number of options outstanding (in shares)	4,143
Weighted average remaining contractual term, outstanding (in years)	9 years 1 month 13 days
Weighted average exercise price (in dollars per share)	$ 267.92
Number of shares, options vested and exercisable (in shares)	862
Weighted average exercise price, options vested and exercisable (in dollars per share)	$ 267.92