Goodwill and Intangible Assets - Schedule of Goodwill and Intangible Assets (Details) (USD $) In Thousands, unless otherwise specified	May 31, 2014	May 31, 2013	May 31, 2012
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 1,337,285	$ 1,044,222	$ 724,687
Other intangible assets	892,511	691,508
Less accumulated amortization	357,338	290,660
Other intangible assets, net	535,173	400,848
Customer-Related Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangible assets	714,704	559,884
Less accumulated amortization	317,629	262,649
Trademarks, finite life [member]
Finite-Lived Intangible Assets [Line Items]
Other intangible assets	6,140	6,390
Less accumulated amortization	4,147	3,967
Technology-Based Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangible assets	25,700	15,000
Less accumulated amortization	3,531	1,248
Contract-based intangible assets [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangible assets	145,967	110,234
Less accumulated amortization	$ 32,031	$ 22,796