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Patent Assets, Net (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Finite-Lived Intangible Assets [Line Items]
Amortization of patent assets	$ 0.4	$ 0.4	$ 0.8	$ 0.7
Patents [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization of patent assets	$ 23.7	$ 20.1	$ 46.3	$ 37.7
Minimum [Member] \| Patents [Member]
Finite-Lived Intangible Assets [Line Items]
Patent assets, useful life			24 months
Maximum [Member] \| Patents [Member]
Finite-Lived Intangible Assets [Line Items]
Patent assets, useful life			60 months
Weighted Average [Member] \| Patents [Member]
Finite-Lived Intangible Assets [Line Items]
Patent assets, useful life			45 months

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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