Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 2,287.9	$ 3,419.3
Marketable securities	0.0	1,473.5
Inventory	2,982.4	1,344.4
Other current assets	974.1	1,417.6
Total current assets	8,454.1	9,791.2
Marketable securities	0.1	705.7
Property, plant and equipment, net	3,301.6	3,298.6
Operating lease assets	460.9	403.9
Intangible assets, net	7,344.6	1,850.1
Goodwill	6,807.5	5,749.0
Deferred tax asset	1,069.8	1,226.4
Investments and other assets	754.6	1,529.2
Total assets	28,193.2	24,554.1
Current liabilities:
Current portion of term loan	500.0	0.0
Taxes payable	243.8	259.9
Accounts payable	440.1	491.5
Accrued expense and other	3,838.4	2,521.4
Total current liabilities	5,022.3	3,272.8
Notes payable and term loan	6,786.4	6,281.0
Deferred tax liability	728.1	334.7
Long-term operating lease liabilities	428.8	333.0
Other long-term liabilities	747.9	944.2
Total liabilities	13,713.5	11,165.7
Commitments, contingencies and guarantees
Biogen Idec Inc. shareholders' equity
Preferred stock, par value $0.001 per share	0.0	0.0
Common stock, par value $0.0005 per share	0.1	0.1
Additional paid-in capital	242.2	73.3
Accumulated other comprehensive income (loss)	(159.3)	(164.9)
Retained earnings	17,377.9	16,466.5
Treasury stock, at cost	(2,977.1)	(2,977.1)
Total Biogen Inc. shareholders’ equity	14,483.8	13,397.9
Noncontrolling interests	(4.1)	(9.5)
Total equity	14,479.7	13,388.4
Total liabilities and equity	28,193.2	24,554.1
Nonrelated Party
Current assets:
Accounts receivable, net	1,781.4	1,705.0
Related Party
Current assets:
Accounts receivable, net	$ 428.3	$ 431.4