XML 28 R33.htm IDEA: XBRL DOCUMENT v2.4.0.6
Nature of Business and Basis of Presentation - Additional Information (Detail) (USD $)
 12 Months Ended 1 Months Ended
Dec. 31, 2009
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2008
Jan. 31, 2012
Financing
3.5% exchangeable senior notes due 2032
Jan. 09, 2012
Financing
3.5% exchangeable senior notes due 2032
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]            
Cash and cash equivalents $ 52,258,000 $ 116,602,000 $ 31,442,000 $ 14,239,000    
Convertible senior notes           150,000,000
Convertible senior notes, stated interest rate           3.50%
Convertible senior notes, maturity date         Jan. 15, 2032  
Proceeds from private placement of convertible senior notes $ 5,600,000       $ 144,300,000