Convertible Debentures and Credit Arrangements - Credit Arrangements Narrative (Detail) - Credit Arrangements [Member]	9 Months Ended
	Sep. 30, 2015 USD ($)
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)	$ 25,000,000.0
Sublimit facility attached on revolving credit facility	20,000,000
Amount available for borrowing under revolving credit facility	$ 18,700,000
After Amendment [Member]
Debt Instrument [Line Items]
Credit facility maturity date	Dec. 21, 2015
Landlord Of Compu Com Systems Incs Dallas Headquarters [Member]
Debt Instrument [Line Items]
Letter of credit under the credit facility	$ 6,300,000
Letter of credit expiration date	Mar. 19, 2019