Stock-Based Compensation - Stock Option Activity (Details) - Employee Stock Options - USD ($)	6 Months Ended		12 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Number of Shares
Outstanding at the beginning of the period (in shares)	1,748,877
Granted (in shares)	599,740
Exercised (in shares)	0	(138,000)
Outstanding at the end of the period (in shares)	2,348,617		1,748,877
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 15.04
Granted (in dollars per share)	29.40
Outstanding at the end of the period (in dollars per share)	$ 18.70		$ 15.04
Weighted Average
Remaining Contractual Life (Years)	9 years 1 month 2 days		9 years 4 months 17 days
Aggregate Intrinsic Value (in dollars)	$ 46,569,629		$ 8,224,947
Exercisable and Vested and Expected to Vest
Number of Shares - exercisable (in shares)	389,060
Weighted Average Exercise Price - exercisable (in dollars per share)	$ 9.74
Number of Shares - vested and expected to vest (in shares)	2,285,137
Weighted Average Exercise Price - vested and expected to vest (in dollars per share)	$ 19.16
Remaining Contractual Life (Years) - vested and expected to vest	9 years 1 month 6 days
Aggregate Intrinsic Value - vested and expected to vest (in dollars)	$ 44,312,789