Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 1,074.4	$ 1,049.9
Inventory	2,516.8	2,527.4
Other current assets	1,165.3	1,182.0
Total current assets	6,756.2	6,859.3
Property, plant and equipment, net	3,275.3	3,309.7
Operating lease assets	428.1	420.0
Intangible assets, net	8,284.7	8,363.0
Goodwill	6,227.4	6,219.2
Deferred tax asset	898.3	928.6
Investments and other assets	697.6	745.0
Total assets	26,567.6	26,844.8
Current liabilities:
Current portion of term loan	250.0	150.0
Taxes payable	231.2	257.4
Accounts payable	387.0	403.3
Accrued expense and other	2,354.6	2,623.6
Total current liabilities	3,222.8	3,434.3
Notes payable and term loan	6,290.1	6,788.2
Deferred tax liability	658.1	641.8
Long-term operating lease liabilities	406.5	400.0
Other long-term liabilities	777.1	781.1
Total liabilities	11,354.6	12,045.4
Commitments, contingencies and guarantees
Biogen Inc. shareholders’ equity:
Preferred stock, par value $0.000 per share	0.0	0.0
Common stock, par value $— per share	0.1	0.1
Additional paid-in capital	329.5	302.5
Accumulated other comprehensive income (loss)	(160.5)	(153.7)
Retained earnings	18,021.0	17,627.6
Treasury stock, at cost	(2,977.1)	(2,977.1)
Total equity	15,213.0	14,799.4
Total liabilities and equity	26,567.6	26,844.8
Nonrelated Party
Current assets:
Accounts receivable, net of allowance for doubtful accounts of $2.2 and $2.4, respectively	1,604.5	1,664.1
Related Party
Current assets:
Accounts receivable, net of allowance for doubtful accounts of $2.2 and $2.4, respectively	$ 395.2	$ 435.9