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Leases - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Lessor and Lessee Lease Description [Line Items]
Operating lease, option to extend, existence	true
Operating lease, option to terminate, existence	true
Short-term lease cost		$ 400,000
Variable lease cost	$ 700,000	900,000
Future operating lease payments	5,554,000		$ 300,000
Allowance for credit losses for our investment in sales type leases	$ 0	$ 0
Minimum [Member]
Lessor and Lessee Lease Description [Line Items]
Operating lease, remaining lease terms	2 months
Operating lease, options to terminate term	3 months
Maximum [Member]
Lessor and Lessee Lease Description [Line Items]
Operating lease, remaining lease terms	55 months
Operating lease, renewal term	2 years
Short-term lease cost	$ 100,000
Lessor sales type lease arrangement terms for network equipments	5 years

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Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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