Aggregate Purchase Price of Acquisitions (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Business Acquisition [Line Items]
Cash	$ 229,684	$ 479,661	$ 190,430
Promissory notes	70,670	38,461	77,760
Deferred consideration	19,998	11,695	2,474
Contingent consideration	15,070	8,182	16,061
Total purchase price	$ 335,422	$ 537,999	$ 286,725

Fair Value of the liabilities incurred by the acquirer to former owners of the acquiree, including the fair value of any contingent consideration. If liabilities transferred as consideration remain within the combined entity after the business combination (for example, because the assets or liabilities were transferred to the acquiree rather than to its former owners), and the acquirer therefore retains control of them; in that situation, the acquirer measures those liabilities at their carrying amounts immediately before the acquisition date.

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+ Details