Income Taxes - Components of the Company's Deferred Income Tax Assets (Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Convertible bond hedge	$ 17,197	$ 21,412
Accrued product returns and rebates	15,123	13,205
Accrued compensation and stock based compensation	10,349	8,218
Non-recourse liability related to sale of future royalties	5,320	5,571
Research and development credit carryforwards	3,817	3,817
Amortization of intangibles	4,617	3,289
Net operating loss carryforwards	2,245	2,900
Operating lease liability	8,187
Inventory	1,385	499
Alternative Minimum Tax (AMT) credit	926	978
Other	199	1,268
Total deferred tax assets	69,365	61,157
Less: valuation allowance	(11)	(9)
Total deferred tax asset, net of valuation allowance	69,354	61,148
Deferred tax liability:
Debt discount on 2023 Notes	(14,109)	(17,568)
Patent infringement legal costs	(10,613)	(10,697)
Operating lease assets	(5,237)
Depreciation	(2,778)	(236)
IRC Section 481(a) liability	(2,126)	(2,964)
Unrealized gain on marketable securities	(2,428)	0
Total deferred tax liabilities	(37,291)	(31,465)
Net deferred tax assets	$ 32,063	$ 29,683