Goodwill and Other Intangible Assets (Schedule of the Changes in the Carrying Amount of Goodwill) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2010	Dec. 31, 2011
Goodwill [Roll Forward]
Beginning Balance	$ 441,347	$ 452,914
Purchase price adjustment in connection with the acerno acquisition	11,567
Ending balance	$ 452,914	$ 452,914

Carrying amount as of the balance sheet date, which is the cumulative amount paid and (if applicable) the fair value of any noncontrolling interest in the acquiree, adjusted for any amortization recognized prior to the adoption of any changes in generally accepted accounting principles (as applicable) and for any impairment charges, in excess of the fair value of net assets acquired in one or more business combination transactions.

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