Goodwill and Acquired Intangible Assets Schedule of the Changes in the Carrying Amount of Goodwill (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012
Changes in the carrying amount of goodwill
Beginning balance	$ 723,701	$ 452,914
Additions	35,606	270,787
Disposals	(1,939)	0
Ending balance	$ 757,368	$ 723,701

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-Section 50

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Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

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Amount of divestiture of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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