Share Repurchase Activity (Detail) (USD $) In Thousands, except Share data	3 Months Ended				9 Months Ended
	Sep. 30, 2011		Sep. 30, 2010		Sep. 30, 2011		Sep. 30, 2010
Stockholders Equity Note [Line Items]
Number of shares repurchased	1,543,069	[1]	48,904	[1]	3,886,521	[1]	3,188,945	[1]
Cost of repurchased shares (in thousands)	$ 53,354	[2]	$ 1,372	[2]	$ 141,214	[2]	$ 76,475	[2]

[1] The nine months ended September 30, 2011 includes 500,000 shares the Company repurchased directly from ValueAct Capital Master Fund L.P. in a private transaction.

[2] As of September 30, 2011, the Company had $363.0 million remaining for share repurchases under its $500.0 million share repurchase program.