Quarterly Results of Operations (Unaudited) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Data [Abstract]
Total revenue	$ 2,563.3	$ 2,334.1	$ 2,277.8	$ 2,080.8	$ 2,085.5	$ 1,982.2	$ 1,872.7	$ 1,730.0	$ 9,256.0	$ 7,670.4	$ 6,493.9
Gross profit	2,433.8	2,202.7	2,153.3	1,951.2	1,951.7	1,859.1	1,745.7	1,621.4	8,741.0	7,177.9
Income tax provision	184.5	14.2	114.6	108.2	96.9	69.0	109.0	52.6	421.5	327.5	215.5
Net income	$ 561.0	$ (34.1)	$ 356.2	$ 718.9	$ 613.9	$ 508.5	$ 597.8	$ 279.7	$ 1,602.0	$ 1,999.9	$ 1,449.9
Net income per share attributable to Celgene
Basic (in dollars per share)	$ 0.71	$ (0.04)	$ 0.45	$ 0.90	$ 0.77	$ 0.64	$ 0.75	$ 0.34	$ 2.02	$ 2.49	$ 1.75
Diluted (in dollars per share)	$ 0.69	$ (0.04)	$ 0.43	$ 0.86	$ 0.74	$ 0.61	$ 0.72	$ 0.33	$ 1.94	$ 2.39	$ 1.68
Weighted average shares:
Basic (in shares)	785.8	791.1	793.0	798.9	800.2	799.6	799.6	811.5	792.2	802.7	827.7
Diluted (in shares)	816.5	791.1	825.3	834.1	834.6	832.8	831.0	845.1	824.9	836.0	860.6