Goodwill and Other Intangible Assets - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
	May 31, 2012
Goodwill and Intangible Assets Disclosure [Line Items]
Weighted-average amortization period for aggregate net intangible assets	10 years 292 days
Contractual agreements and customer relationships
Goodwill and Intangible Assets Disclosure [Line Items]
Weighted-average amortization period for aggregate net intangible assets	11 years 73 days
Contractual agreements and customer relationships | Maximum
Goodwill and Intangible Assets Disclosure [Line Items]
Life of intangible assets	15 years
Intellectual property
Goodwill and Intangible Assets Disclosure [Line Items]
Weighted-average amortization period for aggregate net intangible assets	8 years 256 days
Intellectual property | Maximum
Goodwill and Intangible Assets Disclosure [Line Items]
Life of intangible assets	9 years
Trade Names
Goodwill and Intangible Assets Disclosure [Line Items]
Weighted-average amortization period for aggregate net intangible assets	2 years
Trade Names | Maximum
Goodwill and Intangible Assets Disclosure [Line Items]
Life of intangible assets	2 years
Telmar Network Technology, Inc.
Goodwill and Intangible Assets Disclosure [Line Items]
Acquired intangible assets	49.9
Amount of goodwill	60.9
Telmar Network Technology, Inc. | Intellectual property
Goodwill and Intangible Assets Disclosure [Line Items]
Life of intangible assets	9 years
Acquisition of intangible assets	8.6
Telmar Network Technology, Inc. | Trade Names
Goodwill and Intangible Assets Disclosure [Line Items]
Life of intangible assets	2 years
Acquisition of intangible assets	2.7
Telmar Network Technology, Inc. | Customer Relationships
Goodwill and Intangible Assets Disclosure [Line Items]
Life of intangible assets	15 years
Acquisition of intangible assets	38.6