License and collaboration agreements (Details) (USD $)	3 Months Ended								12 Months Ended			3 Months Ended		12 Months Ended						12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2012 Adamas Pharmaceuticals, Inc [Member]	Mar. 31, 2013 Adamas Pharmaceuticals, Inc [Member]	Mar. 31, 2013 Ironwood [Member]	Mar. 31, 2012 Ironwood [Member]	Mar. 31, 2011 Ironwood [Member]	Aug. 31, 2012 Ironwood [Member]	Sep. 30, 2007 Ironwood [Member]	Jul. 31, 2012 Almirall, S.A. [Member]	Mar. 31, 2013 Nabriva Therapeutics [Member]	Mar. 31, 2013 moksha8 [Member]	Oct. 22, 2012 moksha8 [Member]	Mar. 31, 2012 moksha8 [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone payment														$ 230,000,000			$ 85,000,000		$ 40,000,000
Upfront payment												65,000,000
Future milestones payment													95,000,000	100,000,000
Funding amount																				25,000,000	82,700,000
Long term asset included in other assets	114,682,000				5,034,000				114,682,000	5,034,000										25,000,000
Non refundable upfront payment																		70,000,000
Contingent equity investment convertible preferred stock to be paid														25,000,000
Fair value of the investment	38,100,000				27,700,000				38,100,000	27,700,000				38,100,000
Revenues [Abstract]
Net sales	783,186,000	677,967,000	692,017,000	751,766,000	996,909,000	1,161,254,000	1,130,250,000	1,104,135,000	2,904,936,000	4,392,548,000	4,213,126,000			23,728,000	0	0
Cost of sales [Abstract]
Cost of sales									649,083,000	998,087,000	963,981,000			1,010,000	0	0
SG&A [Abstract]
Payment to/ (receipt from) Ironwood for the Commercialization pool														(39,244,000)	(2,425,000)	724,000
R&D [Abstract]
Payment to/ (receipt from) Ironwood for the Development pool														(4,368,000)	2,884,000	19,610,000
Maximum financial financing																						125,000,000
Period to achieve business goal																					2 years
Fixed price to acquire moksha8																					157,000,000
Fixed price at which moksha8 shareholders can put all assets of moksha8																					144,000,000
Activity related to agreement recorded in Consolidated Balance Sheet [Abstract]
Value of call/put option																					10,700,000		0
Loans receivable																					$ 72,000,000		$ 0