The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The risk-free interest rate assumption that is used in valuing an option on its own shares.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Weighted average expected volatility rate of share-based compensation awards.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsWeightedAverageVolatilityRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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.

+ References

No definition available.

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.D.2)
-URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809

+ Details

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_AwardDateAxis=hlit_PurchasePeriodJuly12016Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_EmployeeStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardDateAxis=hlit_PurchasePeriodDecember312015Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardDateAxis=hlit_PurchasePeriodJune302015Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=us-gaap_ScenarioForecastMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardDateAxis=hlit_PurchasePeriodDecember312016Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Employee Benefit Plans and Stock-based Compensation - Summary of Stock Awards Valuation Assumptions (Details) - Employee Stock Purchase Plan - $ / shares	6 Months Ended
	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Purchase Period July 1, 2016 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (years)		6 months 1 day
Volatility		54.00%
Risk-free interest rate		0.40%
Expected dividends		0.00%
Estimated weighted average fair value per share at purchase date		$ 1.19
Purchase Period December 31, 2015 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (years)			6 months 1 day
Volatility			32.00%
Risk-free interest rate			0.10%
Expected dividends			0.00%
Estimated weighted average fair value per share at purchase date			$ 1.64
Purchase Period June 30, 2015 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (years)				6 months 1 day
Volatility				35.00%
Risk-free interest rate				0.10%
Expected dividends				0.00%
Estimated weighted average fair value per share at purchase date				$ 1.75
Scenario, Forecast [Member] \| Purchase Period December 31, 2016 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (years)	6 months 1 day
Volatility	62.00%
Risk-free interest rate	0.40%
Expected dividends	0.00%
Estimated weighted average fair value per share at purchase date	$ 0.98