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Revenue from Contracts with Customers - Narrative (Details) | 3 Months Ended | 6 Months Ended | 12 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | --- | ---
Jun. 30, 2021 USD ($) | Jun. 30, 2020 USD ($) | Jun. 30, 2021 USD ($) numberOfSources | Jun. 30, 2020 USD ($) | Jun. 30, 2021 USD ($) | Jun. 30, 2020 USD ($) | Mar. 31, 2021 USD ($) | Dec. 31, 2020 USD ($) | Mar. 31, 2020 USD ($) | Dec. 31, 2019 USD ($)
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |
Sources of revenue | numberOfSources |  |  | 3 |  |  |  |  |  |  |
Return period |  |  | 1 year |  |  |  |  |  |  |
Deferred revenue | $ 15,019,000 | $ 11,537,000 | $ 15,019,000 | $ 11,537,000 | $ 15,019,000 | $ 11,537,000 | $ 13,656,000 | $ 12,529,000 | $ 12,102,000 | $ 10,498,000
Amortization period | 3 years |  | 3 years |  | 3 years |  |  |  |  |
Contract asset, impairment loss | $ 0 | $ 0 | $ 0 | $ 0 |  |  |  |  |  |
Hardware and other |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |
Reserve for hardware returns |  |  |  |  | 1.00% | 1.00% |  |  |  |
Activation Fees |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |
Deferred revenue | $ 6,500,000 |  | $ 6,500,000 |  | $ 6,500,000 |  |  | $ 7,000,000.0 |  |
Activation Fees | Maximum |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |
Deferred revenue recognition period |  |  | 10 years |  |  |  |  |  |  |
Activation Fees | Minimum |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |
Deferred revenue recognition period |  |  | 12 months |  |  |  |  |  |  |

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- Definition Amortization period of cost capitalized in obtaining or fulfilling contract with customer, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 340 -SubTopic 40 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123353750&loc=SL49131251-203054 + Details
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- Definition Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=123360276&loc=SL49130531-203044 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 8 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130549-203045 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=123360276&loc=SL49130532-203044 + Details
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