Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 570,721	$ 514,542
Marketable securities	1,134,989	1,176,115
Accounts receivable, net	686,848	584,603
Due from unconsolidated joint business	268,395	228,724
Inventory	447,373	326,843
Other current assets	136,011	144,600
Total current assets	3,244,337	2,975,427
Marketable securities	2,036,658	1,416,737
Property, plant and equipment, net	1,742,226	1,571,387
Intangible assets, net	1,631,547	1,608,191
Goodwill	1,201,296	1,146,314
Investments and other assets	274,054	331,548
Total assets	10,130,118	9,049,604
Current liabilities:
Current portion of notes payable and line of credit	453,379	3,292
Taxes payable	20,066	45,939
Accounts payable	203,999	186,448
Accrued expenses and other	979,945	677,210
Total current liabilities	1,657,389	912,889
Notes payable, line of credit and other financing arrangements	687,396	1,060,808
Long-term deferred tax liability	217,272	248,644
Other long-term liabilities	604,266	400,276
Total liabilities	3,166,323	2,622,617
Commitments and contingencies
Biogen Idec Inc. shareholders' equity
Preferred stock, par value $0.001 per share	0	0
Common stock, par value $0.0005 per share	127	128
Additional paid-in capital	3,854,525	4,185,048
Accumulated other comprehensive income (loss)	(55,305)	(26,535)
Retained earnings	4,486,794	3,106,761
Treasury stock, at cost; 17,655 shares and 13,518 shares, respectively	(1,324,618)	(839,903)
Total Biogen Idec Inc. shareholders’ equity	6,961,523	6,425,499
Noncontrolling interests	2,272	1,488
Total equity	6,963,795	6,426,987
Total liabilities and equity	$ 10,130,118	$ 9,049,604