Share-Based Compensation - Share-Based Compensation Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share-based compensation expense
Share-based compensation expense before taxes	$ 24.6	$ (12.5)	$ 93.8	$ 70.1
Unrecognized compensation cost	31.3		31.3
Stock options
Share-based compensation expense
Share-based compensation expense before taxes	5.8	9.2	19.8	34.8
Related income tax benefit	(0.2)	(0.4)	(0.7)	(2.7)
Share-based compensation expense, net of taxes	5.6	8.8	$ 19.1	32.1
Weighted average remaining vesting period			1 year 4 months 24 days
Restricted stock units
Share-based compensation expense
Share-based compensation expense before taxes	6.2	5.5	$ 18.4	15.0
Related income tax benefit	(1.5)	(1.3)	(4.4)	(3.5)
Share-based compensation expense, net of taxes	4.7	4.2	$ 14.0	11.5
Weighted average remaining vesting period			1 year 10 months 24 days
Unrecognized compensation cost	38.2		$ 38.2
Cost of product sales | Stock options
Share-based compensation expense
Share-based compensation expense before taxes	0.0	0.0	0.1	0.3
Cost of product sales | Restricted stock units
Share-based compensation expense
Share-based compensation expense before taxes	0.5	0.3	1.5	1.0
Research and development | Stock options
Share-based compensation expense
Share-based compensation expense before taxes	0.0	0.5	0.4	1.8
Research and development | Restricted stock units
Share-based compensation expense
Share-based compensation expense before taxes	2.0	1.9	6.0	5.4
Selling, general, and administrative | Stock options
Share-based compensation expense
Share-based compensation expense before taxes	5.8	8.7	19.3	32.7
Selling, general, and administrative | Restricted stock units
Share-based compensation expense
Share-based compensation expense before taxes	$ 3.7	$ 3.3	$ 10.9	$ 8.6