Net Carrying Amount of Debt (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
Debt Instrument [Line Items]
Long term debt	$ 1,419,084		$ 1,427,319
Senior Secured Notes
Debt Instrument [Line Items]
Long term debt	821,575		836,888
1.50% Convertible Notes
Debt Instrument [Line Items]
Long term debt	327,354	[1]	323,418
2.50% Convertible Notes
Debt Instrument [Line Items]
Long term debt	$ 270,155	[2]	$ 267,013

[1] Reflects the net debt carrying amount of the 1.50% Convertible Notes in the consolidated balance sheet as of March 31, 2014, in accordance with accounting for convertible notes. The principal amount owed to the holders of the 1.50% Convertible Notes is $400.0 million.

[2] Reflects the net debt carrying amount of the 2.50% Convertible Notes in the consolidated balance sheet as of March 31, 2014, in accordance with accounting for convertible notes. The principal amount owed to the holders of the 2.50% Convertible Notes is $300.0 million.