Share-Based Compensation - Share-Based Compensation Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Share-based compensation expense
Share-based compensation expense before taxes	$ 29.1	$ 51.8	$ 69.2	$ 82.6
Unrecognized compensation cost	35.4		35.4
Stock options
Share-based compensation expense
Share-based compensation expense before taxes	5.7	9.2	14.0	25.6
Related income tax (benefit) expense	(0.2)	1.4	(0.5)	(2.3)
Share-based compensation expense, net of taxes	5.5	10.6	$ 13.5	23.3
Weighted average remaining vesting period			1 year 8 months 12 days
Restricted stock units
Share-based compensation expense
Share-based compensation expense before taxes	6.5	5.5	$ 12.2	9.5
Related income tax (benefit) expense	(1.6)	(1.3)	(2.9)	(2.2)
Share-based compensation expense, net of taxes	4.9	4.2	$ 9.3	7.3
Weighted average remaining vesting period			2 years 2 months 12 days
Unrecognized compensation cost	42.6		$ 42.6
Cost of product sales | Stock options
Share-based compensation expense
Share-based compensation expense before taxes	0.0	0.1	0.1	0.3
Cost of product sales | Restricted stock units
Share-based compensation expense
Share-based compensation expense before taxes	0.5	0.4	1.0	0.7
Research and development | Stock options
Share-based compensation expense
Share-based compensation expense before taxes	0.2	0.4	0.4	1.3
Research and development | Restricted stock units
Share-based compensation expense
Share-based compensation expense before taxes	2.2	2.1	4.0	3.5
Selling, general, and administrative | Stock options
Share-based compensation expense
Share-based compensation expense before taxes	5.5	8.7	13.5	24.0
Selling, general, and administrative | Restricted stock units
Share-based compensation expense
Share-based compensation expense before taxes	$ 3.8	$ 3.0	$ 7.2	$ 5.3