Two-character EDGAR code representing the state or country of incorporation.

No definition available.

Name:	dei_EntityIncorporationStateCountryCode
Namespace Prefix:	dei_
Data Type:	dei:edgarStateCountryItemType
Balance Type:	na
Period Type:	duration

- Definition

Entity incorporation month year of incorporation.

+ References

No definition available.

+ Details

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Namespace Prefix:	dzsi_
Data Type:	xbrli:gYearMonthItemType
Balance Type:	na
Period Type:	duration

- Definition

Increase decrease in concentration risk percentage.

+ References

No definition available.

+ Details

Name:	dzsi_IncreaseDecreaseInConcentrationRiskPercentage
Namespace Prefix:	dzsi_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of major customers.

+ References

No definition available.

+ Details

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Namespace Prefix:	dzsi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Significant Accounting Policies [Line Items]

+ References

No definition available.

+ Details

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Namespace Prefix:	dzsi_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amounts due for billed services rendered or to be rendered, actions taken or to be taken, or a promise to refrain from taking certain actions in accordance with the terms of a legally binding agreement between the Company and, at a minimum, one other party. An example would be amounts billed to customers under contracts or programs but not paid as of the balance sheet date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.3(c))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 912
-SubTopic 310
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=123371682&loc=d3e55302-109406

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e9054-108599

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6351-108592

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=123594938&loc=d3e13531-108611

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-Name Accounting Standards Codification
-Topic 825
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-Section 50
-Paragraph 21
-Subparagraph (a)
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6404-108592

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of allowance for credit loss for right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=123360276&loc=SL49130533-203044

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124255206&loc=SL82895884-210446

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919249-210447

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919249-210447

+ Details

Name:	us-gaap_ContractWithCustomerAssetAccumulatedAllowanceForCreditLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of allowance for credit loss for right to consideration in exchange for good or service transferred to customer when right to consideration is unconditional.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=123360276&loc=SL49130534-203044

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124255206&loc=SL82895884-210446

+ Details

Name:	us-gaap_ContractWithCustomerReceivableAllowanceForCreditLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Cash receipts from customers during the current period which are usually for sales of goods and services.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3536-108585

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

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- Details

Name:	us-gaap_ConcentrationRiskByBenchmarkAxis=us-gaap_SalesRevenueNetMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_MajorCustomersAxis=dzsi_CustomerOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_MajorCustomersAxis=dzsi_CustomerTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_ConcentrationRiskByTypeAxis=us-gaap_GeographicConcentrationRiskMember
Namespace Prefix:
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- Details

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Organization and Summary of Significant Accounting Policies - Additional Information (Details) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021 USD ($) customer	Sep. 30, 2020 customer	Sep. 30, 2021 USD ($) customer	Sep. 30, 2020 customer	Dec. 31, 2020 USD ($) customer	Mar. 31, 2021 USD ($)
Significant Accounting Policies [Line Items]
Entity Incorporation, State or Country Code			DE
Date of entity incorporation			1999-06
Billed amount under agreement	$ 59.0		$ 59.0		$ 17.3
Amount of payments collected			41.7
Allowance for doubtful accounts	$ 17.3		$ 17.3		$ 3.1
Allowance on remaining balance to be recognized						$ 14.2
Customer Concentration Risk \| Sales Revenue, Net
Significant Accounting Policies [Line Items]
Increase (decrease) in concentration risk, percentage			19.00%
Number of major customers \| customer	2	2	2	1
Customer Concentration Risk \| Sales Revenue, Net \| Customer One
Significant Accounting Policies [Line Items]
Concentration risk, percentage	15.00%	23.00%	18.00%	16.00%
Customer Concentration Risk \| Sales Revenue, Net \| Customer Two
Significant Accounting Policies [Line Items]
Concentration risk, percentage	11.00%	12.00%	12.00%
Customer Concentration Risk \| Accounts receivable
Significant Accounting Policies [Line Items]
Number of major customers \| customer			2		2
Customer Concentration Risk \| Accounts receivable \| Customer One
Significant Accounting Policies [Line Items]
Concentration risk, percentage			18.00%		17.00%
Customer Concentration Risk \| Accounts receivable \| Customer Two
Significant Accounting Policies [Line Items]
Concentration risk, percentage			15.00%		16.00%
Geographic Concentration Risk \| Accounts receivable \| Foreign Countries
Significant Accounting Policies [Line Items]
Concentration risk, percentage			80.00%		89.00%