Summary of significant accounting policies (Details) (USD $)	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 739,702,000	$ 701,158,000
Less: accumulated depreciation	362,742,000	341,138,000
Property, plant and equipment, net	376,960,000	360,020,000
Amount of construction in progress included in Property, plant and equipment	39,200,000	56,800,000
Estimated cost to complete	104,400,000
Revenue Recognition [Abstract]
Number of weeks before settlement of deductions for chargebacks, lower range (in weeks)	2
Number of weeks before settlement of deductions for chargebacks, upper range (in weeks)	3
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Amount of accumulated other comprehensive income, foreign currency translation	1,400,000	9,100,000
Amount of accumulated other comprehensive income, pension liability adjustments	(8,800,000)	(11,300,000)
Amount of accumulated other comprehensive income, unrealized gain (losses) on securities	17,500,000	(700,000)
Income Tax Uncertainties [Abstract]
Percentage of likelihood before tax benefits be recognized	greater than 50 percent
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	64,725,000	59,317,000	64,242,000
Presentation of Comprehensive Income [Member]
New accounting pronouncements [Abstract]
New accounting pronouncement, name	Presentation of Comprehensive Income
New accounting pronouncement, description	In June 2011, the FASB issued ASU 2011-05, Comprehensive Income: Presentation of Comprehensive Income. This ASU amends FASB ASC Topic 220, Comprehensive Income, to require an entity to present the total of comprehensive income, the components of net income and the components of other comprehensive income either in a single continuous statement of comprehensive income or in two separate but consecutive statements. This standard became effective for the Company on April 1, 2012 and the adoption of this standard did not have a significant impact on the Company's financial statements.
Stock Compensation Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	64,725,000	59,317,000	64,242,000
Compensation expense, net of tax	45,700,000	44,300,000	41,300,000
Weighted average period of compensation cost is expected to be recognized	2 years 3 months 18 days
Amount of unrecognized compensation cost for unvested stock options	121,200,000
Summary of weighted average assumptions used in determining fair value of stock options [Abstract]
Expected dividend yield (in hundredths)	0.00%	0.00%	0.00%
Expected volatility (in hundredths)	25.10%	27.49%	27.32%
Risk-free interest rate (in hundredths)	1.20%	1.40%	2.00%
Expected life of options	7 years	7 years	7 years
Savings and profit sharing plan [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Employer contributions	45,900,000	43,400,000	41,400,000
Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	32,740,000	32,113,000
Buildings and Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	333,577,000	286,835,000
Buildings and Improvements [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	10 years
Buildings and Improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	50 years
Machinery, Equipment and Other [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	373,385,000	382,210,000
Machinery, Equipment and Other [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	3 years
Machinery, Equipment and Other [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	10 years
Nabriva Therapeutics [Member]
Long-term receivables [Abstract]
Long term receivables, net	25,400,000
moksha8 [Member]
Long-term receivables [Abstract]
Long term receivables, net	$ 82,700,000