Loss per Share (Details) (USD $)	3 Months Ended			3 Months Ended			3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Mar. 31, 2014 Convertible Debt [Member]	Mar. 31, 2013 Convertible Debt [Member]	Jun. 30, 2012 Convertible Debt [Member]	Mar. 31, 2014 Option [Member]	Mar. 31, 2013 Option [Member]	Mar. 31, 2014 Restricted Stock [Member]	Mar. 31, 2013 Restricted Stock [Member]
Schedule of Earnings per Share Basic and Diluted [Line Items]
Net income attributable to The Medicines Company	$ (4,996,000)	$ (11,573,000)
Weighted average common shares outstanding, basic (shares)	64,152,000	54,047,000
Plus: net effect of dilutive stock options, restricted common shares and shares issuable upon conversion of Notes (shares)	0	0
Weighted average common shares outstanding, diluted (shares)	64,152,000	54,047,000
Loss per share attributable to The Medicines Company, basic (USD per share)	$ (0.08)	$ (0.21)
Loss per share attributable to The Medicines Company, diluted (USD per share)	$ (0.08)	$ (0.21)
Antidilutive common stock shares excluded from computation of earnings per share				1,535,376	873,776		2,128,222	2,705,911	373,897	407,922
Convertible senior notes (due 2017)	$ 238,683,000		$ 236,088,000			$ 275,000,000
Interest rate						1.375%
Shares exercisable upon conversion	9,800,000.0
Strike price (USD per share)	$ 34.2