Document and Entity Information (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Jun. 30, 2012	Jul. 27, 2012	Mar. 31, 2012
Entity Information [Line Items]
Accounts Receivable Allowances	$ 9,719		$ 11,428
Entity Registrant Name	STERIS CORP
Entity Central Index Key	0000815065
Document Type	10-Q
Document Period End Date	Jun. 30, 2012
Amendment Flag	false
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--03-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		58,091,568
Serial preferred shares without par value	$ 0		$ 0
Serial preferred shares authorized	3,000,000		3,000,000
Serial preferred shares issued	0		0
Serial preferred shares outstanding	0		0
Common shares without par value	$ 0		$ 0
Common shares authorized	300,000,000		300,000,000
Common shares issued	70,040,000		70,040,000
Common shares outstanding	58,082,000		57,733,000
Treasury Stock, Shares	11,958,000		12,307,000