Summary of Significant Accounting Policies - Revenue Recognition (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenue Recognition
Sales return period prior to expiry date			6 months
Sales return period subsequent to expiry date			12 months
Milestone revenues recorded	$ 1,300,000	$ 0	$ 1,300,000	$ 0
Selling, general and administrative
Advertising Expense
Advertising costs	$ 9,800,000	$ 5,000,000	$ 16,500,000	$ 11,400,000