Summary of Significant Accounting Policies - Narrative (Details)			1 Months Ended					2 Months Ended	3 Months Ended				12 Months Ended
	Nov. 02, 2016	Feb. 13, 2015 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Nov. 30, 2016 USD ($)	Jan. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2016	Mar. 31, 2017 USD ($) vendor	Dec. 31, 2016 USD ($)	Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($)
Revenue Recognition, Milestone Method [Line Items]
Impairment intangible assets									$ 0		$ 0
Goodwill impairment loss									0		0
Advertising and marketing costs									$ 5,936,000		$ 2,404,000
Cephalon, Inc.
Revenue Recognition, Milestone Method [Line Items]
Proceeds from milestone payment		$ 30,000,000	$ 25,000,000			$ 30,000,000	$ 15,000,000					$ 30,000,000
Milestone payment						$ 15,000,000
Licensing agreement, proceeds from unique billing code				$ 40,000,000	$ 40,000,000					$ 40,000,000
Proceeds on additional milestone sales based			$ 25,000,000
Royalty revenue, percentage of net sales		20.00%
Argatroban and Bendeka
Revenue Recognition, Milestone Method [Line Items]
Number of vendors | vendor									1
Bendeka
Revenue Recognition, Milestone Method [Line Items]
Period after quarter commercial partners report net product sales									25 days
EP-1101
Revenue Recognition, Milestone Method [Line Items]
Period after quarter commercial partners report net product sales									60 days
Minimum | Cephalon, Inc.
Revenue Recognition, Milestone Method [Line Items]
Royalty revenue, percentage of net sales	20.00%	20.00%		20.00%
Maximum | Cephalon, Inc.
Revenue Recognition, Milestone Method [Line Items]
Royalty revenue, percentage of net sales				25.00%	25.00%			25.00%
Teva Pharmaceuticals | Cephalon, Inc.
Revenue Recognition, Milestone Method [Line Items]
Milestone payment benchmark, net sales									$ 500,000,000				$ 500,000,000