Term Loan (Details)			12 Months Ended
	Jun. 22, 2016 USD ($)	Jun. 17, 2016 USD ($) loans	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Jun. 30, 2016 USD ($)
Debt Instrument [Line Items]
Proceeds from borrowing under term loan			$ 19,768,000	$ 0	$ 0
Term loan, less debt issuance costs			$ 19,802,000	$ 0
Debt Financing Agreement
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 30,000,000.0
Number of term loans | loans		2
Debt instrument, face amount						$ 20,000,000.0
Period to borrow additional funds - achievement of a defined milestone event until the earlier		60 days
Period for principal and interest payments		24 months
Stated interest rate, percentage		8.51%
Prepayment fee, option one			2.00%
Prepayment fee, option two			1.00%
Debt extinguishment fee			5.50%
Term loan, less debt issuance costs			$ 20,000,000
Amounts borrowed			20,000,000
Deferred finance costs			$ 200,000			$ 200,000
Debt instrument effective rate			8.98%
Debt Financing Agreement | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate, percentage		0.44%
Debt Financing Agreement Tranche A
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 20,000,000.0
Proceeds from borrowing under term loan	$ 20,000,000
Term loan, less debt issuance costs			$ 20,000,000
Debt Financing Agreement Tranche B
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 10,000,000.0