Convertible Debentures and Credit Arrangements - Credit Arrangements - Additional Information (Detail) (Credit Arrangements, USD $)	9 Months Ended
	Sep. 30, 2013
Debt Instrument [Line Items]
Maximum aggregate amount of revolving credit facility in the form of borrowings, guarantees and issuances of letters of credit (subject to a $20 million sublimit)	$ 50,000,000
Sublimit facility attached on revolving credit facility	20,000,000
Amount of depository, operating accounts, the lesser and investment and securities accounts required to be maintained at the lending bank	80,000,000
Percentage of depository, operating accounts, the lesser and investment and securities accounts required to be maintained at the lending bank	75.00%
Amount available for borrowing under revolving credit facility	43,700,000
After Amendment
Debt Instrument [Line Items]
Credit facility maturity date	Dec. 31, 2014
Landlord of CompuCom Systems
Debt Instrument [Line Items]
Letter of credit under the credit facility	$ 6,300,000
Letter of credit expiration date	Mar. 19, 2019