Details of One Point Five Zero Percent Convertible Notes Reflected on Unaudited Condensed 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 | 1.50% Senior Subordinated Notes Due March 15, 2018
Debt Instrument [Line Items]
Equity component carrying amount		49,931	49,931
Unamortized discount		38,127	42,547
Long term debt		$ 361,873	$ 357,453

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