Acquisitions - Preliminary Purchase price allocations (Details) - USD ($) $ in Thousands	Aug. 01, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Recognized amounts of identifiable assets acquired and liabilities assumed:
Goodwill		$ 59,640	$ 42,403	$ 42,403
Elauwit Networks, LLC
Consideration:
Cash paid	$ 15,576
Holdback consideration	13,000
Contingent consideration	961
Acquisition purchase consideration	29,537
Recognized amounts of identifiable assets acquired and liabilities assumed:
Accounts receivable	4,494
Prepaid expenses and other current assets	1,687
Property and equipment	195
Other non-current assets	177
Accounts payable	(2,049)
Accrued expenses and other liabilities	(683)
Deferred revenue	(3,854)
Other non-current liabilities	(307)
Net tangible liabilities acquired	(340)
Goodwill	17,237
Total purchase price	29,537
Elauwit Networks, LLC | Backlog
Recognized amounts of identifiable assets acquired and liabilities assumed:
Intangibles	$ 7,030
Weighted Average Estimated Useful Life (years)	5 years
Elauwit Networks, LLC | Customer relationships
Recognized amounts of identifiable assets acquired and liabilities assumed:
Intangibles	$ 2,490
Weighted Average Estimated Useful Life (years)	10 years
Elauwit Networks, LLC | Partner relationships
Recognized amounts of identifiable assets acquired and liabilities assumed:
Intangibles	$ 1,200
Weighted Average Estimated Useful Life (years)	10 years
Elauwit Networks, LLC | Transition services agreement
Recognized amounts of identifiable assets acquired and liabilities assumed:
Intangibles	$ 540
Weighted Average Estimated Useful Life (years)	2 years
Elauwit Networks, LLC | Non-compete agreement
Recognized amounts of identifiable assets acquired and liabilities assumed:
Intangibles	$ 1,380
Weighted Average Estimated Useful Life (years)	3 years