Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 4,108.0	$ 1,573.8
Marketable securities	1,808.0	2,115.2
Accounts receivable, net	1,939.2	1,787.0
Due from anti-CD20 therapeutic programs	553.5	532.6
Inventory	890.8	902.7
Other current assets	895.9	962.0
Total current assets	10,195.4	7,873.3
Marketable securities	1,200.2	3,057.3
Property, plant and equipment, net	3,334.7	3,182.4
Intangible assets, net	3,794.5	3,879.6
Goodwill	4,907.8	4,632.5
Deferred tax assets	2,277.4	595.9
Investments and other assets	380.1	431.6
Total assets	26,090.1	23,652.6
Current liabilities:
Current portion of notes payable	3.3	3.2
Taxes payable	231.9	68.2
Accounts payable	345.8	395.5
Accrued expenses and other	2,571.1	2,901.3
Total current liabilities	3,152.1	3,368.2
Notes payable	5,929.4	5,935.0
Deferred tax liabilities	1,331.1	122.6
Other long-term liabilities	1,640.0	1,628.7
Total liabilities	12,052.6	11,054.5
Commitments and contingencies
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	0.0	97.8
Accumulated other comprehensive loss	(303.9)	(318.4)
Retained earnings	17,334.6	15,810.4
Treasury stock, at cost	(2,977.1)	(2,977.1)
Total Biogen Inc. shareholders’ equity	14,053.7	12,612.8
Noncontrolling interests	(16.2)	(14.7)
Total equity	14,037.5	12,598.1
Total liabilities and equity	$ 26,090.1	$ 23,652.6