Subsequent Events - Narrative (Detail) (USD $)	3 Months Ended	9 Months Ended	1 Months Ended
Sep. 30, 2012	Sep. 30, 2012	Nov. 06, 2012 Convertible Senior Notes 4.00 Percent Due 2015 [Member]
Subsequent Event [Line Items]
Repurchase of convertible senior notes			$ 166,400,000
Net payment from extinguishment of 4% Convertible Senior Notes	$ 357,220,000	$ 357,220,000	$ 206,900,000

The cash outflow for incremental, external costs directly pertaining to an early extinguishment of debt, including legal costs and prepayment penalties, and excluding interest and repayment of debt principal.

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration