Income Taxes - Additional Information (Detail) (USD $)	1 Months Ended	12 Months Ended
	Jun. 30, 2010	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income tax benefit		$ 105,000	$ 80,000	$ 78,000
Additional income tax provision	800,000
Decreases in basic net income per share				$ 0.04
Decreases in diluted net income per share				$ 0.03
Current period excess stock-based compensation tax deduction		500,000	1,300,000	600,000
Net unrecognized tax benefits		236,000	461,000	455,000
Interest and penalties associated with unrecognized tax benefits		430,000	42,000	104,000
Interest and penalties accrued		464,000	213,000
State and Local Jurisdiction [Member]
State NOL carryforwards		100,000	200,000	700,000
Remaining state tax NOL carryforwards		7,800,000
Portion of state NOL carryforwards, not able to be utilized before expiration		6,800,000	6,900,000	6,100,000
Federal benefit		$ 300,000	$ 300,000	$ 300,000