Earnings Per Share (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Calculation of earnings per share
Net income attributable to Celgene	$ 279,398,000	$ 155,352,000	$ 534,988,000	$ 389,794,000
Weighted-average shares (in thousands):
Basic	462,625,000	460,309,000	464,300,000	460,112,000
Effect of dilutive securities:
Options, restricted stock units, warrants and other incentives	7,337,000	7,116,000	6,658,000	7,445,000
Diluted	469,962,000	467,425,000	470,958,000	467,557,000
Net income per share
Basic	$ 0.60	$ 0.34	$ 1.15	$ 0.85
Diluted	$ 0.59	$ 0.33	$ 1.14	$ 0.83
Earnings Per Share (Textuals) [Abstract]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	21,840,944	21,757,310	25,951,468	21,140,616
Approved common share repurchase amount	$ 2,000,000,000		$ 2,000,000,000
Common stock repurchased as on date	20,126,697		20,126,697
common stock repurchased during period	4,054,689