Business combinations (Details) (USD $)	12 Months Ended		0 Months Ended	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Apr. 13, 2011 Clinical Data [Member]	Mar. 31, 2013 Clinical Data [Member]	Mar. 31, 2013 Clinical Data [Member] Five Year Milestone [Member]	Mar. 31, 2013 Clinical Data [Member] Six Year Milestone [Member]	Mar. 31, 2013 Clinical Data [Member] Seven Year Milestone [Member]
Business Acquisition [Line Items]
Date of business acquisition			Apr. 13, 2011
Business acquisition, cost acquired entity, description of purchase price components (in dollars per share)			$ 30
Amount of contingent consideration to be paid after reaching milestone per a Contingent Value Rights agreement (CVR) (in dollars per share)			$ 6		$ 1	$ 2	$ 3
Basis for amount relating to contingent consideration arrangements					if U.S. net sales of Viibryd, over four consecutive fiscal quarters within the first 5 years from the date of the close, reach or exceed $800 million,	if U.S. net sales of Viibryd, over four consecutive fiscal quarters within the first 6 years from the date of the close, reach or exceed $1.1 billion	if U.S. net sales of Viibryd, over four consecutive fiscal quarters within the first 7 years from the date of the close, reach or exceed $1.5 billion
Amount of future milestones to be reached or exceeded					$ 800,000,000	$ 1,100,000,000	$ 1,500,000,000
Range of undiscounted amounts we may be required to pay under the CVR, minimum	0
Range of undiscounted amounts we may be required to pay under the CVR, maximum	275,000,000
Fair value of contingent consideration			25,219,000	0
Business combination contingent consideration change in amount adjustment				25,200,000
Cash			14,214,000
Inventory			8,919,000
Prepaid and other current assets			1,208,000
Property, plant and equipment			906,000
Other assets			8,650,000
Short term debt			(725,000)
Accounts payable			(11,391,000)
Accrued expenses			(25,059,000)
Deferred tax liabilities			(371,764,000)
Acquired contingent acquisition liabilities			(11,000,000)
Intangible assets			990,000,000
Goodwill	713,091,000	713,091,000	698,126,000
Total Net Assets Acquired			1,302,084,000
Cash paid				1,276,865,000
Fair value of contingent consideration			25,219,000	0
Total purchase price				$ 1,302,084,000
Sales of Lexapro as percentage of the Company's total sales (in hundredths)	7.00%	48.00%
Intangible asset recorded at acquisition related to Viibryd, amortization period	12 years