Subsequent Event - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012
Subsequent Event [Line Items]
Aggregate Credit Facility	$ 50.0
Loan and security agreement with Silicon Valley Bank
Subsequent Event [Line Items]
Revolving Line Of Credit	35.0
Conventional affirmative and negative covenants | Maximum
Subsequent Event [Line Items]
Leverage Ratio	3.50
Conventional affirmative and negative covenants | Minimum
Subsequent Event [Line Items]
Interest Coverage Ratio	3.0
Compliance | Maximum
Subsequent Event [Line Items]
Leverage Ratio	3.25
Compliance | Minimum
Subsequent Event [Line Items]
Interest Coverage Ratio	3.0
Senior Unsecured Revolving Credit Facility
Subsequent Event [Line Items]
Revolving Line Of Credit	200.0
Line of Credit Maximum borrowing Capacity	$ 200.0