Intangible assets (Details) - USD ($)			12 Months Ended
	Aug. 28, 2014	Jun. 15, 2009	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Intangible assets
Accumulated amortization			$ (12,935,000)	$ (11,198,000)
Intangible assets, net			12,543,000	14,616,000
Write off of capitalized patent filing costs			395,000
Payment made to acquire asset			59,000	5,000	$ 361,000
Intangible assets, gross			25,478,000	25,814,000
Amortization expense			1,737,000	1,737,000	1,660,000
Aggregate amortization of intangible assets for each of the next five years and thereafter
2020			1,737,000
2021			1,737,000
2022			1,737,000
2023			1,642,000
2024			1,333,000
Thereafter			3,871,000
Finite lived intangible assets, net			12,057,000
Proprietary modified-release drug delivery technology
Intangible assets
Amount of finite-lived intangibles		$ 15,600,000
Intangible assets - Useful life		20 years
Intangible assets, gross			15,600,000	15,600,000
Tussionex ANDA
Intangible assets
Payment made to acquire asset	$ 4,200,000
Legal fees	90,000
Earnout fair value	589,000
Intangible assets, gross			4,829,000	4,829,000
Tussionex ANDA | Other income (expense)
Intangible assets
Increase (decrease) in fair value of earnout liability			(7,000)	(133,000)	$ (62,000)
CPI Profit Sharing
Intangible assets
Payment made to acquire asset	2,000,000
Legal fees	$ 43,000
Intangible assets, gross			2,043,000	2,043,000
Patents
Intangible assets
Intangible assets, gross			1,971,000	2,307,000
Other
Intangible assets
Intangible assets, gross			$ 1,035,000	$ 1,035,000
Tussionex ANDA and CPI profit sharing
Intangible assets
Intangible assets - Useful life	10 years