Condensed Consolidated Balance Sheets (Unaudited) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Current assets:
Cash and cash equivalents	$ 697,526	$ 759,598
Marketable securities	629,218	448,146
Accounts receivable, net	666,960	605,329
Due from unconsolidated joint business	184,871	222,459
Inventory	308,254	289,066
Other current assets	201,794	215,822
Total current assets	2,688,623	2,540,420
Marketable securities	1,183,559	743,101
Property, plant and equipment, net	1,712,869	1,641,634
Intangible assets, net	1,678,867	1,772,826
Goodwill	1,146,314	1,146,314
Investments and other assets	211,747	248,198
Total assets	8,621,979	8,092,493
Current liabilities:
Current portion of notes payable, line of credit and other financing arrangements	131,981	137,153
Taxes payable	10,330	84,517
Accounts payable	170,746	162,529
Accrued expenses and other	641,273	665,923
Total current liabilities	954,330	1,050,122
Notes payable and line of credit	1,062,986	1,066,379
Long-term deferred tax liability	196,784	200,950
Other long-term liabilities	351,685	325,599
Total liabilities	2,565,785	2,643,050
Commitments and contingencies (Notes 2, 11, 16, 18 and 20)
Biogen Idec Inc. shareholders' equity
Preferred stock, par value $0.001 per share	0	0
Common stock, par value $0.0005 per share	127	124
Additional paid-in capital	4,224,865	3,895,103
Accumulated other comprehensive income (loss)	25,713	(21,610)
Retained earnings	2,454,848	1,872,481
Treasury stock, at cost	(728,503)	(349,592)
Total Biogen Idec Inc. shareholders' equity	5,977,050	5,396,506
Noncontrolling interests	79,144	52,937
Total equity	6,056,194	5,449,443
Total liabilities and equity	$ 8,621,979	$ 8,092,493