Income Taxes (Tables)

6 Months Ended

Jun. 30, 2021

Income Tax Disclosure [Abstract]

Reconciliation between the U.S. federal statutory tax rate and effective tax rate

A reconciliation between the U.S. federal statutory tax rate and our effective tax rate is summarized as follows:

	For the Three Months Ended June 30,				For the Six Months Ended June 30,
	2021		2020		2021		2020
Statutory rate	21.0	%	21.0	%	21.0	%	21.0	%
State taxes	1.3		0.4		1.1		0.5
Taxes on foreign earnings	(7.7)		(3.4)		(9.1)		(3.7)
Tax credits	(2.9)		(1.0)		(3.3)		(1.0)
Purchased intangible assets	(0.8)		0.2		(0.1)		0.2
TECFIDERA impairment	—		2.7		—		1.5
GILTI	1.5		1.5		1.3		1.1
Neurimmune tax impacts	(83.1)		(0.2)		(46.3)		(0.2)
Other	0.4		0.7		0.6		0.4
Effective tax rate	(70.3)	%	21.9	%	(34.8)	%	19.8	%