Summary Of Significant Accounting Policies - Additional Information (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended			112 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012
Summary Of Significant Accounting Policies [Line Items]
Restricted cash	$ 691			$ 691
Stock based compensation expenses	4,880	2,759	3,637	20,181
Weighted average fair value of stock option granted	$ 3.06	$ 4.04	$ 3.26
Minimum
Summary Of Significant Accounting Policies [Line Items]
Property and equipment useful life	3 years
Maximum
Summary Of Significant Accounting Policies [Line Items]
Property and equipment useful life	5 years
Employee Stock Option
Summary Of Significant Accounting Policies [Line Items]
Stock based compensation expenses	3,100	2,100	1,300
Restricted Stock
Summary Of Significant Accounting Policies [Line Items]
Stock based compensation expenses	1,700	635	2,400
Employee and Director Awards
Summary Of Significant Accounting Policies [Line Items]
Stock based compensation expenses	4,900	2,800	3,600
Non Employee Awards
Summary Of Significant Accounting Policies [Line Items]
Stock based compensation expenses			$ 27