Details of 1.875% Convertible Notes Reflected on Condensed Consolidated Balance Sheet (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012		Dec. 31, 2011
Debt Instrument [Line Items]
Net debt carrying amount	$ 631,304		$ 633,389
1.875% Convertible Notes
Debt Instrument [Line Items]
Equity component carrying amount	41,309		41,309
Unamortized discount	3,949		8,545
Net debt carrying amount	$ 283,551	[1]	$ 278,955

[1] Reflects the net debt carrying amount of the 1.875% Convertible Notes in the consolidated balance sheet as of March 31, 2012, in accordance with accounting for convertible notes. The principal amount owed to the holders of the 1.875% Convertible Notes is $287.5 million.