Net Carrying Amount of Debt (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Debt Instrument [Line Items]
Long term debt	$ 911,718		$ 633,389
Senior Secured Notes
Debt Instrument [Line Items]
Long term debt	600,000
2.50% Convertible Notes
Debt Instrument [Line Items]
Long term debt	254,718	[1]	243,164
Ecko Note
Debt Instrument [Line Items]
Long term debt	57,000		67,000
Asset-Backed Notes
Debt Instrument [Line Items]
Long term debt			44,270
1.875% Convertible Notes
Debt Instrument [Line Items]
Long term debt			$ 278,955

[1] Reflects the net debt carrying amount of the 2.50% Convertible Notes in the consolidated balance sheet as of December 31, 2012, in accordance with accounting for convertible notes. The principal amount owed to the holders of the 2.50% Convertible Notes is $300.0 million.