Commitments and Contingencies - Additional Information (Detail)		1 Months Ended		3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015 USD ($)	Apr. 30, 2014 USD ($)	May. 31, 2013 USD ($) shares	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2012 USD ($)	Feb. 28, 2015 USD ($)	Feb. 28, 2015 CAD	Jul. 31, 2014 USD ($)
Loss Contingencies [Line Items]
Upfront payment paid									$ 300,000
Payment in cash upon closing of financing		$ 11,000,000
Milestone payment upon regulatory authority approval		3,000,000
Manufacturing costs obligation												$ 100,000
Milestone payment not accrued	$ 3,000,000			$ 3,000,000		$ 3,000,000
Payments to contract research organization				600,000		1,600,000
Cumulative unpaid accruing dividends in arrears	18,500,000					$ 18,500,000		$ 14,400,000
Novosom License Agreement [Member]
Loss Contingencies [Line Items]
Shares of common stock issued in settlement of first milestone payment | shares			2,108,870
Fair marker value of common stock issued			$ 100,000
Maximum [Member]
Loss Contingencies [Line Items]
Aggregate milestone payment									$ 14,500,000
Minimum [Member]
Loss Contingencies [Line Items]
Payment for financing		$ 35,000,000
Vancouver Facility [Member]
Loss Contingencies [Line Items]
Operating lease agreement expiration date						Feb. 27, 2018
Letter of credit issued | CAD											CAD 50,000
Collateralized restricted deposit										$ 50,000
Total rent expense for operating leases				$ 100,000	$ 14,000	$ 100,000	$ 22,000
Series B Redeemable Convertible Preferred Stock [Member]
Loss Contingencies [Line Items]
Preferred stock, cumulative dividend percentage rate						8.00%
Cumulative unpaid accruing dividends in arrears	9,300,000					$ 9,300,000		8,400,000
Series B-1 Redeemable Convertible Preferred Stock [Member]
Loss Contingencies [Line Items]
Preferred stock, cumulative dividend percentage rate						8.00%
Cumulative unpaid accruing dividends in arrears	1,700,000					$ 1,700,000		1,500,000
Series C Redeemable Convertible Preferred Stock [Member]
Loss Contingencies [Line Items]
Preferred stock, cumulative dividend percentage rate						8.00%
Cumulative unpaid accruing dividends in arrears	1,600,000					$ 1,600,000		1,100,000
Series D Redeemable Convertible Preferred Stock [Member]
Loss Contingencies [Line Items]
Preferred stock, cumulative dividend percentage rate						8.00%
Cumulative unpaid accruing dividends in arrears	$ 5,900,000					$ 5,900,000		$ 3,400,000