Organization And Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	1 Months Ended	9 Months Ended		12 Months Ended	9 Months Ended		3 Months Ended		9 Months Ended
	Mar. 31, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011	Sep. 30, 2012 Minimum	Sep. 30, 2012 Maximum	Sep. 30, 2012 General and administrative expense	Sep. 30, 2011 General and administrative expense	Sep. 30, 2012 General and administrative expense	Sep. 30, 2011 General and administrative expense
Significant Accounting Policies [Line Items]
Date of incorporation		May 24, 1999
State of incorporation		Delaware
Principal operation beginning date		1999-11
Shares of common stock issued under inital public offering (in number of shares)	7,500,000
Common stock shares, initial public offering, issue price per share (in usd per share)	$ 13
Proceeds from initial public offering, net of underwriting discounts and commissions	$ 90,500,000	$ 0	$ 90,539,000
Offering expenses	3,700,000
Additional shares of common stock sold by certain existing stockholders	4,575,000
Common stock sold by certain existing stockholders, price per share (in usd per share)	$ 13
Transaction costs associated with business combinations							0	0	700,000	0
Identified intangible assets amortization period					2 years	10 years
Impairment charges related to identified intangible assets		$ 0		$ 0