Acquisition of TelWorx Communications LLC - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Business Acquisition [Line Items]
Legal settlement date	Mar. 27, 2013
Settlement agreement fair value		$ 5.4
Settlement agreement remaining consideration		4.3
Asset purchase agreement contingent consideration		0.6
Asset purchase agreement escrow deposit		0.5
TelWorx Communications LLC [Member]
Business Acquisition [Line Items]
Purchase price acquisition, fair value	16.1
Cash paid	16.0
Contingent consideration related to claims escrow	1.1
Potential earn-out at fair value		$ 1.0