Acquisition (Details) - USD ($) $ / shares in Units, $ in Thousands			6 Months Ended	12 Months Ended			18 Months Ended
	Jul. 02, 2014	Jul. 01, 2014	Dec. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Jul. 30, 2016	Apr. 30, 2016
Business Acquisition [Line Items]
Deferred Compensation Arrangement with Individual, Recorded Liability				$ 1,719
Deferred Compensation Arrangement with Individual, Compensation Expense			$ 358		$ 770
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest [Abstract]
Goodwill			40,454	31,343	$ 36,747	$ 40,454	$ 36,747
Service revenue since acquisition							$ 55,100
Business Combination, Pro Forma Information [Abstract]
Business Combination, Indemnification Assets, Amount as of Acquisition Date	$ 6,000
Business Combination, Acquisition Related Costs			$ 1,200
Business Combination, Consideration Transferred, Escrow Released								$ 1,600	$ 4,400
Videotel
Business Acquisition [Line Items]
Business Combination, Contingent Consideration, Liability	$ 47,446
Business combination, consideration transferred, percentage held in escrow		10.00%
Business combination, consideration transferred, period escrow held	21 months
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest [Abstract]
Book value of net assets acquired	$ 1,732
Fair value adjustments to deferred revenue	961
Fair value of tangible net assets acquired	2,693
Identifiable intangibles at acquisition-date fair value	25,524
Deferred income taxes	(3,922)
Goodwill	23,151
Service revenue since acquisition				$ 21,500
Business Combination, Pro Forma Information [Abstract]
Pro forma net revenues						183,886
Pro forma net income						$ 2,386
Basic pro forma net income per share (in dollars per share)						$ 0.15
Diluted pro forma net income per share (in dollars per share)						$ 0.15
Videotel | Subscriber relationships
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest [Abstract]
Identifiable intangibles at acquisition-date fair value	12,759
Videotel | Distribution rights
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest [Abstract]
Identifiable intangibles at acquisition-date fair value	9,814
Videotel | Internally developed software
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest [Abstract]
Identifiable intangibles at acquisition-date fair value	2,160
Videotel | Off-Market Favorable Lease
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest [Abstract]
Identifiable intangibles at acquisition-date fair value	$ 791
Accounts receivable write-offs [Member]
Business Combination, Pro Forma Information [Abstract]
Business Combination, Consideration Transferred, Escrow Released									$ 600