Stock-Based Compensation - Stock Options (Details) - USD ($) $ / shares in Units, $ in Millions			12 Months Ended
	Nov. 14, 2019	May 04, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Number of Shares Under Option
Beginning balance (in shares)			6,177,126	5,814,581	0
Conversion of Impax stock options outstanding on May 4, 2018 (in shares)		3,000,000.0			3,002,669
Options granted (in shares)			0	4,559,820	3,555,808
Options exercised (in shares)			(116,681)	(210,806)	(351,668)
Options forfeited (in shares)			(2,249,216)	(3,986,469)	(392,228)
Ending balance (in shares)	3,600,000		3,811,229	6,177,126	5,814,581
Options exercisable ending balance (in shares)			1,806,223
Weighted- Average Exercise Price per Share
Beginning balance (in dollars per share)			$ 8.87	$ 17.73	$ 0
Conversion of Impax stock options outstanding on May 4,2018 (in dollars per share)					18.90
Options granted (in dollars per share)			0	11.29	16.64
Options exercised (in dollars per share)	$ 2.75		2.75	6.64	10.80
Options forfeited (in dollars per share)			16.09	15.07	23.02
Ending balance (in dollars per share)			4.80	$ 8.87	$ 17.73
Options exercisable ending balance (in dollars per share)			$ 7.07
Weighted- Average Remaining Contractual Life, Outstanding			7 years 10 months 24 days	8 years 2 months 12 days	8 years
Weighted- Average Remaining Contractual Life, Exercisable			7 years 8 months 12 days
Aggregate Intrinsic Value, Outstanding			$ 5.6	$ 8.0	$ 2.6
Aggregate Intrinsic Value, Exercisable			$ 2.0