Prepaid Expenses and Other Assets (Details) - Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Royalty advances	$ 13,518	$ 17,018
Prepaid expenses	2,490	3,606
Income taxes receivable	927	1,274
Other assets	304	0
	$ 17,239	$ 21,898