Reconciliation of Segment Gross Profit to Condensed Consolidated Statements of Operations (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Segment Information [Line Items]
Segment gross profit	$ 83,370	$ 83,435	$ 261,362	$ 241,400
Gross profit	83,077	82,778	260,536	240,066
Cost of revenue [Member]
Segment Information [Line Items]
Stock-based compensation expense	$ (293)	$ (657)	$ (826)	$ (1,334)

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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