Goodwill and Intangible Assets - Goodwill by Segment (Detail) (USD $) In Thousands, unless otherwise specified					3 Months Ended
	Aug. 31, 2014	May 31, 2014	May 31, 2013	May 31, 2012	Aug. 31, 2014 Clinical Devices B.V [Member]	Aug. 15, 2013 Clinical Devices B.V [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance	$ 360,473	$ 360,473	$ 355,637	$ 309,091		$ 4,300
Acquisition					0
Goodwill, Ending Balance	$ 360,473	$ 360,473	$ 355,637	$ 309,091		$ 4,300