Stock Option Plan (Details) (USD $)	0 Months Ended	6 Months Ended	0 Months Ended	6 Months Ended	1 Months Ended			6 Months Ended	1 Months Ended				6 Months Ended
	Jan. 31, 2013	Jun. 30, 2013	Jan. 31, 2013 Options	Jun. 30, 2013 Options	Mar. 31, 2013 Options Various consultants and advisors	Jun. 30, 2013 Options Employees and directors	Jan. 31, 2013 Restricted stock	Jun. 30, 2013 Restricted stock	Jun. 30, 2013 Restricted stock Employees and directors	Apr. 30, 2013 Restricted stock Employee	Jun. 30, 2013 Restricted common stock and options Employees and directors	Jan. 31, 2013 2012 Plan	Jun. 30, 2013 2012 Plan Options Maximum	Jan. 31, 2013 2012 Plan Restricted stock	Jan. 31, 2013 2004 Plan Options
Stock Option Plan
Number of common stock shares initially authorized for grant												1,663,727
Term of option													10 years
Stock-based compensation expense	$ 1,400,000
Options that vested upon consummation of IPO (in shares)			573,424
Weighted average exercise price (in dollars per share)			$ 2.38
Restricted stock that fully vested upon consummation of IPO (in shares)							8,625
Options that commence vesting upon the occurrence of an IPO or a specified financing (in shares)			281,895
Expected stock-based compensation expense on vesting of options (in dollars)		7,400,000	1,800,000						2,000,000
Options
Outstanding balance at the beginning of the period (in shares)				1,819,839											1,819,839
Option Granted (in shares)				141,500	61,500
Options exercised (in shares)				(23,038)
Options forfeited (in shares)				(58,728)
Outstanding balance at the end of the period (in shares)				1,879,573											1,819,839
Options exercisable (in shares)				1,322,795
Weighted Average Exercise Price
Outstanding balance at the beginning of the period (in dollars per share)				$ 2.76
Option Granted (in dollar per shares)				$ 18.96	$ 11.27	$ 24.88
Options exercised (in dollars per share)				$ 2.50
Options forfeited (in dollars per share)				$ 3.24
Outstanding balance at the end of the period (in dollars per share)				$ 3.97
Options exercisable (in dollars per share)				$ 2.96
Weighted-Average Remaining Contractual Life
Outstanding balance at the end of the period				6 years 2 months 26 days
Options exercisable				5 years 1 month 28 days
Aggregate Intrinsic Value
Outstanding balance at the end of the period (in dollars)				37,426,040
Options exercisable (in dollars)				27,616,536
Restricted Stock
Outstanding balance at the beginning of the period (in shares)							34,507	34,507						34,507
Shares granted								231,614		149,614
Outstanding balance at the end of the period (in shares)								266,121						34,507
Vested shares								17,252
Aggregate Intrinsic Value
Outstanding balance at the end of the period (in dollars)								6,344,235
Vested shares (in dollars)								$ 411,288
Restricted common stock and options granted											82,000
Number of shares of common stock that can be purchased											80,000
Fair market value of stock granted (in dollars per share)									$ 24.88	$ 13.11
Number of restricted common stock shares vest ratably over specified period										112,212
Number of restricted common stock shares that vest based on meeting certain market capitalization thresholds										37,402
Vesting period									4 years	5 years
Weighted average period recognized		1 year 6 months