Sale of Zohydro ER business - Narrative (Details) (USD $)	3 Months Ended		0 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Apr. 24, 2015 employee	Apr. 23, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net product revenue	$ 0	$ 6,485,000
Stock-based compensation	1,871,000	2,507,000
Zohydro ER | Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Stock-based compensation	522,000	463,000
Amortization	124,000	85,000
Subsequent event
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of positions committed to be eliminated			100
Expected number of additional positions to be eliminated			16
Subsequent event | Silicon Valley Bank
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Liquidity ratio				1.25
Subsequent event | Zohydro ER
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of business			80,000,000
Restricted cash			10,000,000
Potential indemnification period			12 months
Common stock received			11,900,000
Potential additional cash payments			283,500,000
Regulatory milestone payment			12,500,000
Potential sales milestone			271,000,000
Subsequent event | Zohydro ER | Ferrimill Limited
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net product revenue			900,000
Subsequent event | Zohydro ER | Ferrimill Limited | Indemnification Agreement [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Maximum indemnification amount			5,000,000