Details of Two Point Five Zero Percent Convertible Notes Reflected on Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands		Mar. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Long term debt	[1]	$ 1,443,245	$ 1,449,392
Convertible Notes | 2.50% Senior Subordinated Notes Due June 2016
Debt Instrument [Line Items]
Equity component carrying amount		35,996	35,996
Unamortized discount		2,388	5,952
Long term debt		$ 297,612	$ 294,048

[1] Carrying amounts include aggregate unamortized debt discount and debt issuance costs.