Accrued Expenses and Other Current Liabilities (Parenthetical) (Detail)	Jun. 30, 2011 USD ($)		Sep. 30, 2010 USD ($)		Dec. 31, 2010 SpinVox Acquisitions USD ($)	Dec. 31, 2010 SpinVox Acquisitions EUR (€)	Jun. 30, 2011 SpinVox Acquisitions Standby Letters of Credit USD ($)	Jun. 30, 2011 SpinVox Acquisitions Standby Letters of Credit EUR (€)	Dec. 31, 2010 SpinVox Acquisitions Standby Letters of Credit EUR (€)
Schedule of Accrued Liabilities [Line Items]
Sales and marketing incentives	$ 17,174,000	[1]	$ 40,780,000	[1]	$ 23,400,000	€ 18,000,000
Restricted cash placed in an irrevocable standby letter of credit account							$ 7,200,000	€ 5,000,000	€ 18,000,000

[1] The decrease in accrued sales and marketing incentives was driven by an €18.0 million ($23.4 million equivalent) payment in December 2010 for a fixed obligation assumed in connection with our acquisition of SpinVox. The related €18.0 million of restricted cash was placed in an irrevocable standby letter of credit account at the end of fiscal year 2010 and was released upon satisfaction of the liability in December 2010. At June 30, 2011, we have an additional €5.0 million ($7.2 million equivalent) of restricted cash that has been placed in an irrevocable standby letter of credit for a related liability.