Consolidated Financial Statement Components - Depreciation, Amortization and Accretion (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Property, Plant and Equipment [Line Items]
Depreciation	$ 932	$ 1,170	$ 3,094	$ 3,903
Amortization
Intangible assets	0	625	417	1,875
Capitalized software development costs	1,482	422	3,779	422
Total amortization	1,482	1,047	4,196	2,297
Accretion	154	118	462	353
Total depreciation, amortization and accretion expense	2,568	2,335	7,752	6,553
Leasehold improvements
Property, Plant and Equipment [Line Items]
Depreciation	18	13	52	43
Asset retirement costs
Property, Plant and Equipment [Line Items]
Depreciation	22	161	66	482
Paging and computer equipment
Property, Plant and Equipment [Line Items]
Depreciation	871	1,237	2,923	4,110
Furniture, fixtures and vehicles
Property, Plant and Equipment [Line Items]
Depreciation	$ 65	$ 81	$ 185	$ 232

The aggregate amount of recurring noncash expense charged against earnings in the period to allocate the cost of assets over their estimated remaining economic lives.

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The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Amount of accretion expense recognized during the period that is associated with an asset retirement obligation. Accretion expense measures and incorporates changes due to the passage of time into the carrying amount of the liability.

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Amount of expense for amortization of capitalized computer software costs.

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The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

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The aggregate net amount of depreciation, amortization, and accretion recognized during an accounting period. As a noncash item, the net amount is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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