Goodwill and Intangibles, Net, Measured on Non-Recurring Basis Using Market Approach (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule Of Goodwill And Intangible Assets [Line Items]
Goodwill (annual impairment assessment)	$ 107,794	$ 21,843	$ 19,622
Acquired intangible assets (periodic assessment, as necessary)	84,715	14,431
Fair Value, Inputs, Level 3
Schedule Of Goodwill And Intangible Assets [Line Items]
Goodwill (annual impairment assessment)	107,794	21,843
Acquired intangible assets (periodic assessment, as necessary)	84,715	14,431
Intangible Assets, Net (Including Goodwill), Total	$ 192,509	$ 36,274