Significant Accounting Policies (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) segment	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of operating business segments | segment	1
Cash and cash equivalents	$ 108,927	$ 141,824	$ 155,908	$ 118,521
Restricted cash collateral for corporate credit card program and letters of credit	390	0
Prepaid manufacturing costs	1,400	0
Undistributed earnings in foreign subsidiaries	$ 1,500
Maximum days MYALEPT can be held as inventory	21 days
Unrecognized tax benefits	$ 7,660	$ 7,278	$ 5,557	$ 1,846
Computer Software and Hardware | Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property and equipment, estimated useful lives	3 years
Computer Software and Hardware | Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property and equipment, estimated useful lives	5 years
Office Furniture, Fixtures, Research and Other Equipment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property and equipment, estimated useful lives	5 years
Silicon Valley Bank
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restricted cash collateral for corporate credit card program and letters of credit	$ 400