Convertible Notes - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012
Debt Instrument [Line Items]
Payments for note hedge transactions	$ 22,708,000		$ 11,141,000
Proceeds from issuance of warrants	124,775,000
Convertible Senior Notes
Debt Instrument [Line Items]
Purchase price of notes as percentage of principal amount, plus accrued and unpaid interest	100.00%
Conversion rate per $1,000 principal amount of Notes	18.7161
Convertible note, par amount	1,000
Initial conversion price	$ 53.43
Maturity date, convertible note	Dec. 01, 2018
Effective interest rate	5.26%
Net carrying amount	1,110,585,000
Equity component	305,569,000	[1]
Deferred tax liability	37,000,000
Payments for note hedge transactions	206,000,000
Warrant expiration period	2019-03
Strike price of warrants	71.24
Proceeds from issuance of warrants	$ 125,000,000

[1] Recorded in the consolidated balance sheet within additional paid-in capital.