Share-Based Compensation - Benefit recognized (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 (benefit) expense recognized in connection with the STAP
Total share-based compensation expense before tax	$ 29.1	$ 51.8	$ 69.2	$ 82.6
Restricted stock units
Share based compensation (benefit) expense recognized in connection with the STAP
Total share-based compensation expense before tax	6.5	5.5	12.2	9.5
Related income tax benefit	(1.6)	(1.3)	(2.9)	(2.2)
Share-based compensation expense, net of taxes	4.9	4.2	9.3	7.3
STAP awards
Share based compensation (benefit) expense recognized in connection with the STAP
Total share-based compensation expense before tax	16.4	36.7	42.1	46.8
Related income tax benefit	(2.6)	(6.8)	(7.5)	(9.1)
Share-based compensation expense, net of taxes	13.8	29.9	34.6	37.7
Cash payments on awards exercised during the period			42.2	10.8
Cost of product sales \| Restricted stock units
Share based compensation (benefit) expense recognized in connection with the STAP
Total share-based compensation expense before tax	0.5	0.4	1.0	0.7
Cost of product sales \| STAP awards
Share based compensation (benefit) expense recognized in connection with the STAP
Total share-based compensation expense before tax	0.8	1.5	1.9	2.2
Research and development \| Restricted stock units
Share based compensation (benefit) expense recognized in connection with the STAP
Total share-based compensation expense before tax	2.2	2.1	4.0	3.5
Research and development \| STAP awards
Share based compensation (benefit) expense recognized in connection with the STAP
Total share-based compensation expense before tax	2.3	8.7	6.6	10.9
Selling, general, and administrative \| Restricted stock units
Share based compensation (benefit) expense recognized in connection with the STAP
Total share-based compensation expense before tax	3.8	3.0	7.2	5.3
Selling, general, and administrative \| STAP awards
Share based compensation (benefit) expense recognized in connection with the STAP
Total share-based compensation expense before tax	$ 13.3	$ 26.5	$ 33.6	$ 33.7

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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