Details of One Point Five Zero Percent Convertible Notes Reflected on Unaudited Condensed Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Dec. 31, 2015		Dec. 31, 2014
Debt Instrument [Line Items]
Long term debt	$ 1,464,408		$ 1,394,077
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	42,547		60,057
Long term debt	$ 357,453	[1]	$ 339,943

[1] Reflects the net debt carrying amount of the 1.50% Convertible Notes in the consolidated balance sheet as of December 31, 2015, in accordance with accounting for convertible notes. The principal amount owed to the holders of the 1.50% Convertible Notes is $400.0 million.