Debt (Details)		1 Months Ended			3 Months Ended		9 Months Ended
	Mar. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2014	Jun. 30, 2013 USD ($)	Sep. 30, 2016 USD ($) installment loan	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) installment loan	Sep. 30, 2015 USD ($)
Debt
Repayment of long-term debt							$ 5,000,000	$ 0
Paid-in-kind interest							385,000	0
Interest Expense, Debt [Abstract]
End-of-term payment interest							$ 206,000	59,000
Line of Credit | Visium
Debt
Number of term loans | loan					2		2
Maximum borrowing capacity					$ 40,000,000.0		$ 40,000,000.0
Interest rate (as a percent)					12.00%		12.00%
Number of installments | installment					8		8
Term of debt with equal quarterly installments							2 years
Rate for which Company may elect to pay interest in cash (as a percent)					0.090		0.090
Remaining percentage for which interest is paid-in-kind					0.030		0.030
Paid-in-kind interest					$ 385,000
Prepayment allowed		$ 5,000,000
Whole multiple in excess of minimum prepayment		$ 1,000,000
Prepayment premium for prepayment made on or prior to March 31, 2018 (as a percent)		0.240
Prepayment premium for prepayment made after March 31, 2018 and on or prior to March 31, 2019 (as a percent)		0.040
Prepayment premium for prepayment made after March 31, 2019 and on or prior to March 31, 2020 (as a percent)		0.020
Prepayment premium for prepayment made after March 31, 2020 and on or prior to March 31, 2021 (as a percent)		0.010
Period for which lender has rights to participate in equity financings		1 year
Debt principal					25,385,000		$ 25,385,000
Unamortized deferred debt issuance costs					(494,000)		(494,000)
Net debt obligation					24,891,000		24,891,000
Future principal payments
2020					9,519,000		9,519,000
Thereafter					15,866,000		15,866,000
Total					25,385,000		25,385,000
Line of Credit | Visium | Maximum
Debt
Maximum amount allowed to participate in future equity financings					5,000,000.0		5,000,000.0
Line of Credit | Visium | Initial Term Loan
Debt
Drawn down initial term loan	$ 25,000,000
Repayment of long-term debt	$ 5,000,000
Line of Credit | Visium | Second Term Loan
Debt
Maximum borrowing capacity					15,000,000.0		15,000,000.0
Term Loans
Debt
Maximum borrowing capacity				$ 10,000,000.0
Prepayment premium for prepayment made after March 31, 2021 (as a percent)			0
Future principal payments
Amount drawn down				$ 5,000,000
Interest Expense, Debt [Abstract]
Nominal interest					772,000	$ 64,000	1,600,000	189,000
Amortization and write-off of debt discount and debt issuance costs					27,000	7,000	145,000	20,000
Prepayment penalty					0	0	50,000	0
End-of-term payment interest					0	21,000	156,000	60,000
Total					$ 799,000	$ 92,000	$ 1,951,000	$ 269,000