Income Taxes - Additional Information (Detail) (USD $) In Millions	9 Months Ended
	Sep. 30, 2011
Income Taxes [Line Items]
Unrecognized tax benefit	0.6
Reduction in income tax expense if unrecognized tax benefit is recognized	0.4
Total accrued interest and penalties	0.2
Internal Revenue Service (IRS)
Income Taxes [Line Items]
Tax years open to examination	The U.S. federal tax return for 2006 and subsequent years remain open to examination by the Internal Revenue Service ("IRS").
Tax years under examination	Effective July 2011, the Company is under audit examination by the IRS for the 2008 and 2009 tax years.
State and Local Jurisdiction
Income Taxes [Line Items]
Tax years open to examination	Our California and Massachusetts tax returns for the years 2006 and 2007, respectively, and subsequent years remain open to examination.