Debt - Additional Information (Detail)	3 Months Ended		6 Months Ended		1 Months Ended	3 Months Ended	1 Months Ended
	Jun. 30, 2014 USD ($)	Jun. 30, 2013 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2013 USD ($)	Apr. 30, 2014 Senior Subordinated Notes USD ($)	Jun. 30, 2014 Senior Subordinated Notes USD ($)	Mar. 31, 2014 Senior Subordinated Convertible Notes USD ($)	Jul. 31, 2014 Three Point Seven Five Percent Senior Notes Due October Two Thousand Twenty One Subsequent Event USD ($)	Jul. 31, 2014 Three Point Seven Five Percent Senior Notes Due October Two Thousand Twenty One Subsequent Event EUR (€)
Debt Instrument [Line Items]
Debt instrument aggregate principal amount repurchased consideration					$ 523,000,000
Loss on the extinguishment of debt	54,400,000	8,800,000	54,400,000	25,900,000		54,400,000
Private offering senior subordinated convertible notes, aggregate principal amount							690,000,000
Interest rate of debt instrument							1.125%		3.75%
Debt instrument maturity year							2034
Net proceeds after deducting fees and expenses							674,000,000
Initial conversion rate for common stock							13.36
Convertible note, initial conversion price per share							$ 74.86
Principal amount of convertible notes in to shares common stock							1,000
Percentage by which closing sale price of common stock is more than the current conversion price							130.00%
Number of trading days							20 days
Number of Consecutive trading days							30 days
Number Of Trading Days							60 days
Number of consecutive trading days immediately preceding, but excluding, declaration date							10 days
Percentage that distribution has per share value exceeding closing sale price of common stock							10.00%
Percentage of closing sale price of common stock in excess of convertible notes trading price							98.00%
Trading-day period							10 days
Convertible Debt Initial Liability Component							471,000,000
Convertible Debt Equity Component							219,000,000
Effective interest rate							5.50%
Private offering senior notes, aggregate principal amount									300,000,000
Senior notes, maturity period								2021-10
Net proceeds from issuance of senior notes after deducting fees and expenses								$ 400,000,000