Accrued Liabilities and other Long-Term Liabilities (Schedule of Accrued Expenses and Other Long-Term Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accrued expenses:
Professional fees	$ 1,236	$ 1,153
Salaries, bonus and related benefits	6,701	6,683
Research and development	5,007	4,215
Research and development - manufacturing	518	1,017
Research and development - license maintenance fees	461	361
Research and development - milestones	600	0
Accrued royalties payable	2,682	2,320
Accrued coupon expense	10,869	8,391
Other	1,188	1,259
Total accrued expenses	29,262	25,399
Other long-term liabilities:
Deferred rent and long-term lease abandonment charge	1,949	2,136
Partner company note payable, long-term	7,359	4,990
Total other long-term liabilities and partner company note payable, long-term	9,308	7,126
Ximino [Member]
Other long-term liabilities:
Partner company note payable, long-term	3,622	4,990
Oral Acne Product (Isotretinoin) [Member]
Other long-term liabilities:
Partner company note payable, long-term	2,792	0
Anti-itch Product [Member]
Other long-term liabilities:
Partner company note payable, long-term	$ 945	$ 0