Harmonic (HLIT) 10-Q 11 May 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Apr. 03, 2015	Apr. 30, 2015
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	FALSE
Document Period End Date	3-Apr-15
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Trading Symbol	HLIT
Entity Registrant Name	HARMONIC INC
Entity Central Index Key	851310
Current Fiscal Year End Date	-19
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		88,532,963

CONDENSED_CONSOLIDATED_BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (USD $)	Apr. 03, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Current assets:
Cash and cash equivalents	$79,656	$73,032
Short-term investments	22,203	31,847
Accounts receivable, net	75,864	74,144
Inventories	31,518	32,747
Deferred income taxes, short-term	3,375	3,375
Prepaid expenses and other current assets	30,526	17,539
Total current assets	243,142	232,684
Property and equipment, net	27,140	27,221
Goodwill	197,776	197,884
Intangibles, net	8,692	10,599
Other assets	10,097	12,130
Total assets	486,847	480,518
Current liabilities:
Accounts payable	18,497	15,318
Income taxes payable	320	893
Deferred revenue	48,124	38,601
Accrued liabilities	29,248	35,118
Total current liabilities	96,189	89,930
Income taxes payable, long-term	5,032	4,969
Deferred tax liabilities, long-term	3,095	3,095
Other non-current liabilities	11,007	10,711
Total liabilities	115,323	108,705
Commitments and contingencies (Note 16)
Stockholders’ equity:
Preferred stock, $0.001 par value, 5,000 shares authorized; no shares issued or outstanding	0	0
Common stock, $0.001 par value, 150,000 shares authorized; 88,750 and 87,700 shares issued and outstanding at April 3, 2015 and December 31, 2014, respectively	89	88
Additional paid-in capital	2,265,055	2,261,952
Accumulated deficit	-1,890,904	-1,888,247
Accumulated other comprehensive loss	-2,716	-1,980
Total stockholders’ equity	371,524	371,813
Total liabilities and stockholders’ equity	$486,847	$480,518

CONDENSED_CONSOLIDATED_BALANCE1

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Apr. 03, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Preferred stock, par value	$0.00	$0.00
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$0.00	$0.00
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	88,750,000	87,700,000
Common stock, shares outstanding	88,750,000	87,700,000

CONDENSED_CONSOLIDATED_STATEME

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Apr. 03, 2015	Mar. 28, 2014
Income Statement [Abstract]
Product revenue	$80,473	$88,260
Service revenue	23,543	19,772
Net revenue	104,016	108,032
Product cost of revenue	35,460	44,606
Service cost of revenue	13,528	11,114
Total cost of revenue	48,988	55,720
Gross profit	55,028	52,312
Operating expenses:
Research and development	22,329	23,888
Selling, general and administrative	31,196	33,547
Amortization of intangibles	1,446	1,950
Restructuring and related charges	44	149
Total operating expenses	55,015	59,534
Income (loss) from operations	13	-7,222
Interest income, net	55	77
Other income (expense), net	-506	12
Loss on impairment of long-term investment	-2,505	0
Loss before income taxes	-2,943	-7,133
Benefit from income taxes	-286	-1,723
Net loss	($2,657)	($5,410)
Net loss per share:
Basic	($0.03)	($0.06)
Diluted	($0.03)	($0.06)
Shares used in per share calculation:
Basic	88,655	97,921
Diluted	88,655	97,921

CONDENSED_CONSOLIDATED_STATEME1

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Apr. 03, 2015	Mar. 28, 2014
Net loss	($2,657)	($5,410)
Other comprehensive income (loss) before tax:
Unrealized losses arising during the period	-184	0
Gains reclassified into earnings	-49	0
Change in unrealized losses on cash flow hedges:	-233	0
Change in unrealized gains on available-for-sale securities:	485	7
Change in foreign currency translation adjustments	-984	40
Other comprehensive income (loss) before tax	-732	47
Provision for (benefit from) income taxes	4	-1
Other comprehensive income (loss), net of tax	-736	48
Total Comprehensive loss	($3,393)	($5,362)

CONDENSED_CONSOLIDATED_STATEME2

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Apr. 03, 2015	Mar. 28, 2014
Cash flows from operating activities:
Net loss	($2,657)	($5,410)
Adjustments to reconcile net loss to net cash provided by operating activities:
Amortization of intangibles	1,907	6,666
Depreciation	3,493	4,227
Stock-based compensation	4,134	3,807
Loss on impairment of long-term investment	2,505	0
Deferred income taxes, net	0	3,510
Provision for excess and obsolete inventories	454	722
Allowance for doubtful accounts, returns and discounts	-367	-536
Excess tax benefits from stock-based compensation	-120	-185
Other non-cash adjustments, net	154	462
Changes in assets and liabilities:
Accounts receivable	-1,353	-1,927
Inventories	775	5,900
Prepaid expenses and other assets	-13,062	-6,671
Accounts payable	3,380	-2,533
Deferred revenue	10,105	6,382
Income taxes payable	-501	278
Accrued and other liabilities	-6,819	-3,447
Net cash provided by operating activities	2,028	11,245
Cash flows from investing activities:
Purchases of investments	0	-14,084
Proceeds from maturities of investments	9,497	15,382
Purchases of property and equipment	-3,651	-3,431
Purchases of long-term investments	85	0
Net cash provided by (used in) investing activities	5,761	-2,133
Cash flows from financing activities:
Payments for repurchase of common stock	-5,182	-29,075
Proceeds from (repurchases of) common stock issued to employees	4,032	-1,377
Excess tax benefits from stock-based compensation	120	185
Net cash used in financing activities	-1,030	-30,267
Effect of exchange rate changes on cash and cash equivalents	-135	18
Net increase (decrease) in cash and cash equivalents	6,624	-21,137
Cash and cash equivalents at beginning of period	73,032	90,329
Cash and cash equivalents at end of period	$79,656	$69,192

Basis_of_Presentation_and_Sign

Basis of Presentation and Significant Accounting Policies	3 Months Ended
	Apr. 03, 2015
Accounting Policies [Abstract]
Basis of Presentation and Significant Accounting Policies	BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES
	Basis of Presentation
	The accompanying unaudited condensed consolidated financial statements, in the opinion of management, include all adjustments (consisting only of normal recurring adjustments) which Harmonic Inc. (“Harmonic,” or the “Company”) considers necessary for a fair statement of the results of operations for the interim periods covered and the consolidated financial condition of the Company at the date of the balance sheets. This Quarterly Report on Form 10-Q should be read in conjunction with the Company’s audited consolidated financial statements contained in the Company’s Annual Report on Form 10-K, which was filed with the Securities and Exchange Commission on March 2, 2015 (“2014 Form 10-K”). The interim results presented herein are not necessarily indicative of the results of operations that may be expected for the full fiscal year ending December 31, 2015, or any other future period. The Company’s fiscal quarters are based on 13-week periods, except for the fourth quarter, which ends on December 31.
	The condensed consolidated financial statements include the accounts of the Company and its subsidiaries. All significant intercompany accounts and transactions have been eliminated in consolidation. The year-end condensed balance sheet was derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the United States of America (“U.S. GAAP”).
	Use of Estimates
	The preparation of the condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from those estimates.
	Significant Accounting Policies
	The Company’s significant accounting policies are described in Note 2 to its audited Consolidated Financial Statements included in its 2014 Form 10-K. There have been no significant changes to these policies during the three months ended April 3, 2015.

Recent_Accounting_Pronouncemen

Recent Accounting Pronouncements	3 Months Ended
	Apr. 03, 2015
Accounting Changes and Error Corrections [Abstract]
Recent Accounting Pronouncements	RECENT ACCOUNTING PRONOUNCEMENTS
	On May 28, 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, “Revenue from Contracts with Customers”, requiring an entity to recognize the amount of revenue that reflects the consideration to which it expects to be entitled for the transfer of promised goods or services to customers. The updated standard will replace most existing revenue recognition guidance in U.S. GAAP when it becomes effective and permits the use of either the retrospective or cumulative effect transition method. Early adoption is not permitted. The updated standard becomes effective for the Company in the first quarter of fiscal 2017. In April 2015, the FASB announced a proposal to defer the effective date by one year, with early adoption on the original effective date permitted. The Company has not yet selected a transition method and it is currently evaluating the effect that the updated standard will have on its consolidated financial statements and related disclosures.
	On November 3, 2014, the FASB issued ASU No. 2014-16, “Derivatives and Hedging (Topic 815) - Determining Whether the Host Contract in a Hybrid Financial Instrument Issued in the Form of a Share is More Akin to Debt or to Equity”. ASU 2014-16 was issued to clarify how current U.S. GAAP should be interpreted in evaluating the economic characteristics and risk of a host contract in a hybrid financial instrument that is issued in the form of a share.  In addition, ASU 2014-16 was issued to clarify that in evaluating the nature of a host contract, an entity should assess the substance of the relevant terms and features (that is, the relative strength of the debt-like or equity-like terms and features given the facts and circumstances) when considering how to weight those terms and features. ASU 2014-16 is effective in the fiscal year beginning after December 15, 2015. Early adoption in an interim period is permitted. The Company is currently evaluating the impact of the adoption of ASU 2014-16 on its consolidated financial statements.
	On February 18, 2015, the FASB issued ASU No. 2015-02, “Consolidation (Topic 810) - Amendments to the Consolidation Analysis”, intended to improve targeted areas of consolidation guidance for all entities. ASU 2015-02 is effective in the fiscal year beginning after December 15, 2015. Early adoption in an interim period is permitted. The Company is currently evaluating the impact of the adoption of ASU 2015-02 on its consolidated financial statements.
	On April 15, 2015, the FASB issued ASU No. 2015-05, “Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40) - Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement”. ASU 2015-05 amends ASC 350-40 to provide customers with guidance on whether a cloud computing arrangement contains a software license to be accounted for as internal-use software. ASU No. 2015-05 is effective in the fiscal year beginning after December 15, 2015. Early adoption in an interim period is permitted. The Company is currently evaluating the impact of the adoption of ASU 2015-05 on its consolidated financial statements.

ShortTerm_Investments

Short-Term Investments	3 Months Ended
	Apr. 03, 2015
Cash and Cash Equivalents [Abstract]
Short-Term Investments	SHORT-TERM INVESTMENTS
	The following table summarizes the Company’s short-term investments (in thousands):
		Amortized		Gross		Gross			Estimated
		Cost		Unrealized		Unrealized			Fair Value
				Gains		Losses
	As of April 3, 2015
	State, municipal and local government agencies bonds	$	11,228	$	10	$	—		$	11,238
	Corporate bonds	10,969		1		(5		)	10,965
	Total short-term investments	$	22,197	$	11	$	(5	)	$	22,203
	As of December 31, 2014
	State, municipal and local government agencies bonds	$	13,946	$	16	$	(1	)	$	13,961
	Corporate bonds	17,899		3		(16		)	17,886
	Total short-term investments	$	31,845	$	19	$	(17	)	$	31,847
	The following table summarizes the maturities of the Company’s short-term investments (in thousands):
		3-Apr-15		31-Dec-14
	Less than one year	$	22,203	$	30,946
	Due in 1 - 2 years	—		901
	Total short-term investments	$	22,203	$	31,847
	These available-for-sale investments are presented as “Current Assets” in the Condensed Consolidated Balance Sheet as they are available for current operations. Realized gains and losses from the sale of investments for the three months ended April 3, 2015 and March 28, 2014 were not material.
	As of April 3, 2015 and December 31, 2014, $6.7 million and $8.6 million, respectively, of investments in equity securities of other privately and publicly held companies were considered as long-term investments and were included in “Other assets” in the Condensed Consolidated Balance Sheet (See Note 4, “Investments in Other Equity Securities,” for additional information).
	Impairment of Short-term Investments
	The Company monitors its investment portfolio for impairment on a periodic basis. In the event that the carrying value of an investment exceeds its fair value and the decline in value is determined to be other-than-temporary, an impairment charge is recorded and a new cost basis for the investment is established. A decline of fair value below amortized costs of debt securities is considered other-than-temporary if the Company has the intent to sell the security or it is more likely than not that the Company will be required to sell the security before recovery of the entire amortized cost basis. At the present time, the Company does not intend to sell its investments that have unrealized losses in accumulated other comprehensive loss. In addition, the Company does not believe that it is more likely than not that it will be required to sell its investments that have unrealized losses in accumulated other comprehensive loss before the Company recovers the principal amounts invested. The Company believes that the unrealized losses are temporary and do not require an other-than-temporary impairment, based on its evaluation of available evidence as of April 3, 2015.
	As of April 3, 2015, there were no individual available-for-sale securities in a material unrealized loss position and the amount of unrealized losses on the total investment balance was insignificant.

Investments_in_Other_Equity_Se

Investments in Other Equity Securities	3 Months Ended
	Apr. 03, 2015
Investments, All Other Investments [Abstract]
Investments in Equity Securities	INVESTMENTS IN OTHER EQUITY SECURITIES
	From time to time, the Company may acquire certain equity investments for the promotion of business objectives and these investments are classified as long-term investments and included in "Other assets" in the Condensed Consolidated Balance Sheet.
	On September 2, 2014, the Company acquired a 3.3% interest in Vislink plc (“Vislink”), a U.K. public company listed on the AIM exchange, for $3.3 million, and also made a $3.3 million prepayment for future software license purchases. The investment in Vislink is being accounted for as a cost method investment as the Company does not have significant influence over the operational and financial policies of Vislink. Since the Vislink investment is also an available-for-sale security, its value is marked to market for the difference in fair value at period end. As of April 3, 2015, the carrying value of Vislink was $3.1 million and the accumulated unrealized loss of $0.2 million, net of taxes, on the Vislink investment is included in the Condensed Consolidated Balance Sheet as a component of “Accumulated other comprehensive income (loss)”. As of April 3, 2015, the balance of the prepayment to Vislink for future software license purchase was $1.1 million and it was included in “Prepaid expenses and other current assets” in the Condensed Consolidated Balance Sheet. The Company determined that there were no impairment indicators existing at April 3, 2015 that would indicate that the Vislink investment was impaired and the Company believes the decline in the fair value of the Vislink investment is temporary. As of April 3, 2015, the Company's maximum exposure to loss from the Vislink investment was limited to its initial investment cost of $3.3 million. As of December 31, 2014, the carrying value of Vislink was $2.6 million and the accumulated unrealized loss, net of taxes, was $0.7 million.
	Unconsolidated Variable Interest Entities (“VIE”)
	VJU
	On September 26, 2014, the Company acquired a 19.8% interest in VJU iTV Development GmbH (“VJU”), a software company based in Austria, for $2.5 million. Since VJU's equity is deemed not sufficient to permit it to finance its activities without additional support from its shareholders, VJU is considered a variable interest entity (“VIE”). The Company determined that it is not the primary beneficiary of VJU because its financial interest in VJU's equity and its research and development agreement with VJU do not empower the Company to direct VJU's activities that will most significantly impact VJU's economic performance. VJU is accounted for as a cost method investment as the Company does not have significant influence over the operational and financial policies of VJU.
	The Company attended a VJU board meeting on March 5, 2015 as an observer. At that meeting, the Company was made aware of significant decreases in VJU's business prospects, VJU’S existing working capital and prospects for additional funding, compared to the prior information the Company had received from VJU. Based on the Company’s assessment, the Company determined that its investment in VJU was impaired on an other-than-temporary basis. Factors considered included the severity of the impairment and recent events specific to VJU. Based on the Company's assessment of VJU's expected cash flows, the entire investment is expected to be non-recoverable. As a result, the Company recorded an impairment charge of $2.5 million in the first quarter of 2015. The Company's impairment loss in VJU is limited to its initial cost of investment of $2.5 million as well as the $0.1 million research and development cost expensed in September 2014.
	EDC
	On October 22, 2014, the Company acquired an 18.4% interest in Encoding.com, Inc. (“EDC”), a video transcoding service company headquartered in San Francisco, California, for $3.5 million by purchasing EDC's Series B preferred stock. Since EDC's equity is deemed not sufficient to permit it to finance its activities without additional support from its shareholders, EDC is considered a VIE. The Company determined that it is not the primary beneficiary of EDC because its financial interest in EDC's equity does not empower the Company to direct EDC's activities that will most significantly impact EDC's economic performance. In addition, the Company determined that its investment in EDC's Series B preferred stock does not have the risk and reward characteristics that are substantially similar to EDC’s common stock. Therefore, Harmonic does not hold an investment in EDC’s common stock or in-substance common stock. According to the applicable accounting guidance, the EDC investment is accounted for as a cost-method investment.
	The following table presents the carrying values and maximum exposure of the unconsolidated VIEs as of April 3, 2015 (in thousands):
		Carrying Value		Maximum exposure to loss(1)
	VJU	—		—
	EDC(2)	3,593		3,593
	Total	$	3,593	$	3,593
	(1) The Company did not provide financial support to any of its unconsolidated VIEs and as of April 3, 2015, there were no explicit arrangements or implicit variable interests that could require the Company to provide financial support to any of its unconsolidated VIEs.
	(2) The Company's maximum exposure to loss with respect to EDC as of April 3, 2015 was limited to a total investment cost of $3.6 million, including $0.1 million of transaction costs.
	Each reporting period, the Company reviews all of its unconsolidated VIE investments to determine whether there are any reconsideration events that may result in the Company being a primary beneficiary of the unconsolidated VIE which would then require the Company to consolidate the VIE. The Company also reviews all of its cost-method investments in each reporting period to determine whether a significant event of change in circumstances has occurred that may have an adverse effect on the fair value of each investment.

Derivative_and_Hedgiing_Activi

Derivative and Hedgiing Activities Derivative and Hedging Activities	3 Months Ended
	Apr. 03, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Hedging Activities Disclosure	DERIVATIVES AND HEDGING ACTIVITIES
	The Company uses forward contracts to manage exposures to foreign currency exchange rates. The Company's primary objective in holding derivative instruments is to reduce the volatility of earnings and cash flows associated with fluctuations in foreign currency exchange rates and the Company does not use derivative instruments for trading purposes. The use of derivative instruments expose the Company to credit risk to the extent that the counterparties may be unable to meet their contractual obligations, as such, the potential risk of loss with any one counterparty is closely monitored by the Company.
	Derivatives Designated as Hedging Instruments (Cash Flow Hedges)
	Beginning in December 2014, the Company entered into forward currency contracts to hedge forecasted operating expenses and service costs related to employee salaries and benefits denominated in Israeli shekels (“ILS”) for its subsidiaries in Israel. These ILS forward contacts mature generally within twelve months and are designated as cash flow hedges. For derivatives that are designated as hedges of forecasted foreign currency denominated operating expenses and service costs, the Company assesses effectiveness based on changes in spot currency exchange rates. Changes in spot rates on the derivative are recorded as a component of “Accumulated other comprehensive income (loss)” (“OCI”) in the Condensed Consolidated Balance Sheet until such time as the hedged transaction impacts earnings. The change in fair value of the forward points, which reflects the interest rate differential between the two countries on the derivative, is excluded from the effectiveness assessment. Gains or losses on the derivative representing either hedge ineffectiveness or hedge components excluded from the assessment of effectiveness are recognized in current earnings.
	Derivatives Not Designated as Hedging Instruments (Balance Sheet Hedges)
	Balance sheet hedges consist of foreign currency forward contracts, mature generally within three months, are carried at fair value and they are used to minimize the short-term impact of foreign currency exchange rate fluctuation on cash and certain trade and inter-company receivables and payables. Changes in the fair value of these foreign currency forward contracts are recognized in “Other income (expense), net” in the Condensed Consolidated Statement of Operations and are largely offset by the changes in the fair value of the assets or liabilities being hedged.
	The locations and amounts of designated and non-designated derivative instruments' gains and losses reported in the Company's Condensed Consolidated Statements of Operations were as follows (in thousands):
				Three months ended
		Financial Statement Location		3-Apr-15				28-Mar-14
	Derivatives Designated as Hedging instruments:
	Gains in accumulated OCI on derivatives (effective portion)	Accumulated OCI		$	184			$	—
	Gains reclassified from accumulated OCI into income (effective portion)	Cost of Revenue		$	7			$	—
		Operating Expense		42				—
		Total		$	49			$	—
	Loss recognized in income on derivatives (ineffectiveness portion and amount excluded from effectiveness testing)	Other income (expense), net		$	(42	)		$	—
	Derivatives Not Designated as Hedging instruments:
	Gains (losses) recognized in income	Other income (expense), net		$	252			$	(177	)
	The Company anticipates the accumulated OCI balance of 78,000 at April 3, 2015, relating to net unrealized gains from cash flow hedges, will be reclassified to earnings in 2015.
	The U.S. dollar equivalents of all outstanding notional amounts of foreign currency forward contracts are summarized as follows (in thousands):
		3-Apr-15				31-Dec-14
	Derivatives designated as cash flow hedges:
	Purchase	$	12,728			$	16,903
	Derivatives not designated as hedging instruments:
	Purchase	$	6,585			$	1,043
	Sell	$	9,069			$	4,925
	The locations and fair value amounts of the Company's derivative instruments reported in its Condensed Consolidated Balance Sheets are as follows (in thousands):
				Asset Derivatives									Derivative Liabilities
		Balance Sheet Location		April 3, 2015				December 31, 2014			Balance Sheet Location		April 3, 2015			December 31, 2014
	Derivatives designated as hedging instruments:
	Foreign currency contracts	Prepaid expenses and other current assets		$	57			$	329		Accrued Liabilities		$	—		$	—
				$	57			$	329				$	—		$	—
	Derivatives not designated as hedging instruments:
	Foreign currency contracts	Prepaid expenses and other current assets		$	91			$	12		Accrued Liabilities		$	18		$	7
				$	91			$	12				$	18		$	7
	Total derivatives			$	148			$	341				$	18		$	7
	Offsetting of Derivative Assets and Liabilities
	The Company recognizes all derivative instruments on a gross basis in the Condensed Consolidated Balance Sheet. However, the arrangements with its counterparties allows for net settlement, which are designed to reduce credit risk by permitting net settlement with the same counterparty. To further limit credit risk, the Company also enters into cash collateral security arrangements with the same counterparty. As of April 3, 2015, information related to the offsetting arrangements was as follows (in thousands):
												Gross Amounts of Derivatives Not Offset in the Condensed Consolidated Balance Sheets
		Gross Amounts of Derivatives				Gross Amounts of Derivatives Offset in the Condensed Consolidated Balance sheets			Net Amounts of Derivatives Presented in the Condensed Consolidated Balance Sheets			Financial Instrument			Cash Collateral Pledged			Net Amount
	Derivative Assets	$	148			—			$	148		$	(18	)	—			$	130
	Derivative Liabilities	$	18			—			$	18		$	(18	)	—			$	—
	As of December 31, 2014, there was no potential effect of rights of offset associated with the outstanding foreign currency forward contracts that would result in a net derivative asset or net derivative liability.

Fair_Value_Measurements

Fair Value Measurements	3 Months Ended
	Apr. 03, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS
	The applicable accounting guidance establishes a framework for measuring fair value and requires disclosure about the fair value measurements of assets and liabilities. This guidance requires the Company to classify and disclose assets and liabilities measured at fair value on a recurring basis, as well as fair value measurements of assets and liabilities measured on a nonrecurring basis in periods subsequent to initial measurement, in a three-tier fair value hierarchy as described below.
	The guidance defines fair value as the exchange price that would be received for an asset or paid to transfer a liability, in the principal or most advantageous market for the asset or liability, in an orderly transaction between market participants on the measurement date.
	Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The guidance describes three levels of inputs that may be used to measure fair value:
	•	Level 1 — Observable inputs that reflect quoted prices for identical assets or liabilities in active markets.
	•	Level 2 — Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. The Company primarily uses broker quotes for valuation of its short-term investments. The forward exchange contracts are classified as Level 2 because they are valued using quoted market prices and other observable data for similar instruments in an active market.
	•	Level 3 — Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.
	The Company uses the market approach to measure fair value for its financial assets and liabilities. The market approach uses prices and other relevant information generated by market transactions involving identical or comparable assets or liabilities. During the three months ended April 3, 2015, there were no nonrecurring fair value measurements of assets and liabilities subsequent to initial recognition.
	The following table sets forth the fair value of the Company’s financial assets and liabilities measured at fair value based on the three-tier fair value hierarchy (in thousands):
		Level 1		Level 2		Level 3		Total
	As of April 3, 2015
	Cash equivalents
	Money market funds	$	32,795	$	—	$	—	$	32,795
	Short-term investments
	State, municipal and local government agencies bonds	—		11,238		—		11,238
	Corporate bonds	—		10,965		—		10,965
	Prepaids and other current assets
	Derivative assets	—		148		—		148
	Other assets
	Long-term investment	3,082		—		—		3,082
	Total assets measured and recorded at fair value	$	35,877	$	22,351	$	—	$	58,228
	Accrued liabilities
	Derivative liabilities	$	—	$	18	$	—	$	18
	Total liabilities measured and recorded at fair value	$	—	$	18	$	—	$	18
		Level 1		Level 2		Level 3		Total
	As of December 31, 2014
	Cash equivalents
	Money market funds	$	23,121	$	—	$	—	$	23,121
	Short-term investments
	State, municipal and local government agencies bonds	—		13,961		—		13,961
	Corporate bonds	—		17,886		—		17,886
	Prepaids and other current assets
	Derivative assets	—		341		—		341
	Other assets
	Long-term investment	2,606		—		—		2,606
	Total assets measured and recorded at fair value	$	25,727	$	32,188	$	—	$	57,915
	Accrued liabilities
	Derivative liabilities	$	—	$	7	$	—	$	7
	Total liabilities measured and recorded at fair value	$	—	$	7	$	—	$	7

Balance_Sheet_Components

Balance Sheet Components	3 Months Ended
	Apr. 03, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Balance Sheet Components	BALANCE SHEET COMPONENTS
	The following tables provide details of selected balance sheet components (in thousands):
		3-Apr-15			31-Dec-14
	Accounts receivable, net:
	Accounts receivable	$	80,974		$	81,201
	Less: allowances for doubtful accounts, returns and discounts	(5,110		)	(7,057		)
	Total	$	75,864		$	74,144
	Prepaid expenses and other current assets:
	Prepaid inventories to contract manufacturer(1)	$	14,200		$	—
	Prepaid software license to Vislink(2)	1,090			1,233
	Other Prepayments	9,953			9,713
	Deferred cost of revenue	3,364			2,524
	Income tax receivable	1,664			2,316
	Other	255			1,753
		$	30,526		$	17,539
	(1) In the first quarter of 2015, the Company made a $14.2 million advance payment for future inventory requirements to a supplier in order to secure more favorable pricing. The Company anticipates that this amount will begin to offset in the fourth quarter of 2015 through the first quarter of 2016 against the accounts payable owed to this supplier.
	(2) The prepaid inventories were related to prepayment for software licenses made to Vislink (see Note 4, “Investments in Other Equity Securities,” for additional information on Vislink).
	Inventories:
	Raw materials	$	1,844		$	1,422
	Work-in-process	1,439			1,255
	Finished goods	28,235			30,070
	Total	$	31,518		$	32,747
	Property and equipment, net:
	Furniture and fixtures	$	7,690		$	7,691
	Machinery and equipment	116,895			116,031
	Leasehold improvements	9,550			8,140
	Property and equipment, gross	134,135			131,862
	Less: accumulated depreciation and amortization	(106,995		)	(104,641		)
	Total	$	27,140		$	27,221

Goodwill_and_Identified_Intang

Goodwill and Identified Intangible Assets	3 Months Ended
	Apr. 03, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Identified Intangible Assets	GOODWILL AND IDENTIFIED INTANGIBLE ASSETS
	Goodwill
	The following table presents goodwill by reportable segments (in thousands):
		Video				Cable Edge				Total
	As of December 31, 2014	$	136,975			$	60,909			$	197,884
	Foreign currency translation adjustment	(75		)		(33		)		(108		)
	As of April 3, 2015	$	136,900			$	60,876			$	197,776
	Identified Intangible Assets
	The following is a summary of identifiable intangible assets (in thousands):
				3-Apr-15										31-Dec-14
		Range of Useful Lives		Gross Carrying				Accumulated				Net Carrying		Gross Carrying		Accumulated			Net Carrying
				Amount				Amortization				Amount		Amount		Amortization			Amount
	Identifiable intangibles:
	Developed core technology	4-6 years		$	136,145			$	(135,887	)		$	258	$	136,145	$	(135,426	)	$	719
	Customer relationships/contracts	5-6 years		67,098				(60,001		)		7,097		67,098		(58,784		)	8,314
	Maintenance agreements and related relationships	6-7 years		7,100				(5,763		)		1,337		7,100		(5,534		)	1,566
	Total identifiable intangibles			$	210,343			$	(201,651	)		$	8,692	$	210,343	$	(199,744	)	$	10,599
	Amortization expense for the identifiable purchased intangible assets for the three months ended April 3, 2015 and March 28, 2014 was allocated as follows (in thousands):
			Three months ended
			April 3,				March 28,
			2015				2014
	Included in cost of revenue		$	461			$	4,716
	Included in operating expenses		1,446				1,950
	Total amortization expense		$	1,907			$	6,666
	The estimated future amortization expense of purchased intangible assets with definite lives is as follows (in thousands):
		Cost of Revenue				Operating				Total
						Expenses
	Year ended December 31,
	2015 (remaining 9 months)	$	258			$	4,337			$	4,595
	2016	—				4,097				4,097
	Total future amortization expense	$	258			$	8,434			$	8,692

Restructuring_and_Related_Char

Restructuring and Related Charges	3 Months Ended
	Apr. 03, 2015
Restructuring and Related Activities [Abstract]
Restructuring and Related Charges	RESTRUCTURING AND RELATED CHARGES
	The Company implemented several restructuring plans in the past few years. The goal of these plans was to bring operational expenses to appropriate levels relative to its net revenues, while simultaneously implementing extensive company-wide expense control programs.
	The Company accounts for its restructuring plans under the authoritative guidance for exit or disposal activities. The restructuring and asset impairment charges are included in “Product cost of revenue” and “Operating expenses-restructuring and related charges” in the Condensed Consolidated Statements of Operations. The following table summarizes the restructuring and related charges (in thousands):
		Three months ended
		April 3,			March 28,
		2015			2014
	Restructuring and related charges in:
	Product cost of revenue	$	—		$	79
	Operating expenses-Restructuring and related charges	44			149
		$	44		$	228
	Harmonic 2015 Restructuring
	In the fourth quarter of 2014, the Company approved a new restructuring plan (the “Harmonic 2015 Restructuring Plan”) to reduce 2015 operating costs and the planned restructuring activities involve headcount reduction, exiting certain operating facilities and disposing of excess assets. The Company started the restructuring activities pursuant to this plan in the fourth quarter of 2014 and expects to complete its actions by end of 2015. The Company recorded $2.2 million of restructuring and asset impairment charges recorded under this plan in the fourth quarter of 2014 consisting of a $1.1 million fixed asset impairment charge related to software development costs incurred for a discontinued information technology (“IT”) project, $0.6 million of severance and benefits related to the termination of nineteen employees worldwide, $0.3 million of excess material costs associated with the termination of a research and development project and $0.1 million of other charges. In the three months ended April 3, 2015, the Company recorded an additional 44,000 restructuring charges under the Harmonic 2015 Restructuring Plan primarily related to severance and benefits for two employees.
	The following table summarizes the activity in the Harmonic 2015 restructuring accrual during the three months ended April 3, 2015 (in thousands):
		Severance and benefits			Other charges			Total
	Balance at December 31, 2014	$	305		$	17		$	322
	Restructuring charges	56			—			56
	Adjustments to restructuring provisions	(5		)	(7		)	(12		)
	Cash payments	(312		)	(9		)	(321		)
	Non-cash write-offs	—			2			2
	Balance at April 3, 2015	$	44		$	3		$	47
	Harmonic 2013 Restructuring
	The Company implemented a series of restructuring plans in 2013 to reduce costs and improve efficiencies. These restructuring plans extended to actions taken through the third quarter of fiscal 2014. As a result, the Company recorded restructuring charges of $2.2 million and $0.9 million in fiscal 2013 and fiscal 2014, respectively. The restructuring charges in the three months ended March 28, 2014 were $0.2 million under these plans, consisting of severance and benefits related to the termination of eight employees worldwide and costs associated with vacating from excess facility in France. For a complete discussion of the restructuring actions related to the 2013 restructuring plans, see Note 11, "Restructuring and Asset Impairment Charges," of Notes to Consolidated Financial Statements in the 2014 Form 10-K.

Credit_Facilities

Credit Facilities	3 Months Ended
	Apr. 03, 2015
Debt Disclosure [Abstract]
Credit Facilities	CREDIT FACILITIES
	On December 22, 2014, the Company entered into a Credit Agreement with JPMorgan Chase Bank, N.A. (“JPMorgan”) for a $20.0 million revolving credit facility, with a sublimit of $10.0 million for the issuance of commercial and standby letters of credit on the Company’s behalf. Revolving loans under the Credit Agreement may be borrowed, repaid and re-borrowed until December 22, 2015, at which time all amounts borrowed must be repaid. There were no borrowings under the Credit Agreement during the three months ended April 3, 2015. As of April 3, 2015, the amount available for borrowing under this facility, net of $0.2 million of standby letters of credit, was $19.8 million.
	The revolving loan bears interest, at the Company's election, at either (a) an adjusted LIBOR rate for a term of one, two or three months, plus an applicable margin of 1.75% or (b) the prime rate plus an applicable margin of -1.30%, provided that such rate shall not be less than the one month adjusted LIBOR rate, plus 2.5%. In the event that the balance of the Company’s accounts held with JPMorgan falls below $30.0 million in aggregate total worldwide consolidated cash and short-term investments (the “Consolidated Cash Threshold”) for five consecutive business days, the Company is obligated to pay a one-time facility fee of $50,000 to JPMorgan. The Company is also obligated to pay JPMorgan a non-usage fee equal to the average daily unused portion of the credit facility multiplied by a per annum rate of 0.25% if, during any calendar month, the balance in the Company’s accounts held with JPMorgan falls below the Consolidated Cash Threshold for five consecutive business days.
	The Company will pay a letter of credit fee with respect to any letters of credit issued under the Credit Agreement in an amount equal to (a) in the case of a standby letter of credit, the maximum amount available to be drawn under such standby letter of credit multiplied by a per annum rate of 1.75% and (b) in the case of a commercial letter of credit, the greater of $100 or 0.75% of the original maximum available amount of such commercial letter of credit. The Company will also pay other customary transaction fees and costs in connection with the issuance of letters of credit under the Credit Agreement.
	Obligations under the Credit Agreement are secured only by a pledge of 66 2/3% of the Company’s equity interests in its foreign subsidiary, Harmonic International AG. Additionally, to the extent that the Company in the future forms any direct or indirect, domestic, material subsidiaries, those subsidiaries will be required to provide a guaranty of the Company’s obligations under the Credit Agreement.
	The Credit Agreement contains customary affirmative and negative covenants, including covenants that limit the Company’s and its subsidiaries’ ability to, among other things, incur indebtedness, grant liens, merge or consolidate, dispose of assets, make investments or pay dividends, in each case subject to certain exceptions. The Company is also required to maintain, on a consolidated basis, total cash and marketable securities of at least $35.0 million and EBITDA of at least $20.0 million determined on a rolling four-quarter basis. As of April 3, 2015, the Company was in compliance with the covenants under the Credit Agreement.

Employee_Benefit_Plans

Employee Benefit Plans	3 Months Ended
	Apr. 03, 2015
Postemployment Benefits [Abstract]
Employee Benefit Plans	EMPLOYEE BENEFIT PLANS
	Harmonic grants stock options and restricted stock units (“RSUs”) pursuant to stockholder approved equity incentive plans. These equity incentive plans are described in detail in Note 14, “Employee Benefit Plans”, of Notes to Consolidated Financial Statements in the 2014 Form 10-K.
	Stock Options and Restricted Stock Units
	The following table summarizes the Company’s stock option and RSU unit activity during the three months ended April 3, 2015 (in thousands, except per share amounts):
				Stock Options Outstanding						Restricted Stock Units Outstanding
		Shares		Number			Weighted			Number		Weighted
		Available for		of			Average			of		Average
		Grant		Shares			Exercise Price			Units		Grant
												Date Fair
												Value
	Balance at December 31, 2014	7,480		7,255			$	6.65		2,241		$	6.4
	Authorized			—			—			—		—
	Granted	(3,037	)	1,049			7.58			1,325		7.57
	Options exercised	—		(617	)		5.49			—		—
	Shares released	—		—			—			(925	)	6.56
	Forfeited or cancelled	283		(172	)		6.86			(73	)	6.23
	Balance at April 3, 2015	4,726		7,515			$	6.87		2,568		$	7.01
	The following table summarizes information about stock options outstanding as of April 3, 2015 (in thousands, except per share amounts):
		Number		Weighted				Weighted	Aggregate
		of		Average				Average	Intrinsic
		Shares		Exercise				Remaining	Value
				Price				Contractual
								Term (Years)
	Vested and expected to vest	7,126		$	6.87			3.7	$	6,331
	Exercisable	4,694		6.94				2.5	4,571
	The intrinsic value of options vested and expected to vest and exercisable as of April 3, 2015 is calculated based on the difference between the exercise price and the fair value of the Company’s common stock as of April 3, 2015. The intrinsic value of options exercised is calculated based on the difference between the exercise price and the fair value of the Company's common stock as of the exercise date. The intrinsic value of options exercised during the three months ended April 3, 2015 and March 28, 2014 was $1.3 million and $0.1 million, respectively.
	The following table summarizes information about RSUs outstanding as of April 3, 2015 (in thousands, except per share amounts):
		Number of		Weighted		Aggregate
		Shares		Average		Fair
		Underlying		Remaining		Value
		Restricted		Vesting
		Stock		Period
		Units		(Years)
	Vested and expected to vest	2,359		0.8		$	17,407
	The fair value of RSUs vested and expected to vest as of April 3, 2015 is calculated based on the fair value of the Company's common stock as of April 3, 2015.
	Employee Stock Purchase Plan
	The 2002 Employee Stock Purchase Plan (“ESPP”) provides for the issuance of common stock purchase rights to employees of the Company. The ESPP is intended to qualify as an “employee stock purchase plan” under Section 423 of the Internal Revenue Code. The ESPP enables employees to purchase shares at 85% of the fair market value of the common stock at the beginning or end of the offering period, whichever is lower. Offering periods generally begin on the first trading day on or after January 1 and July 1 of each year. Employees may participate through payroll deductions of 1% to 10% of their earnings. In the event that there are insufficient shares in the plan to fully fund the issuance, the available shares will be allocated across all participants based on their contributions relative to the total contributions received for the offering period.
	401(k) Plan
	The Company has a retirement/savings plan which qualifies as a thrift plan under Section 401(k) of the Internal Revenue Code. This plan allows participants to contribute up to the applicable Internal Revenue Code limitations under the plan. The Company has made discretionary contributions to the plan of 25% of the first 4% contributed by eligible participants, up to a maximum contribution per participant of $1,000 per year. The contributions for the three months ended April 3, 2015 and March 28, 2014 were $161,000 and $173,000, respectively.

StockBased_Compensation

Stock-Based Compensation	3 Months Ended
	Apr. 03, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	STOCK-BASED COMPENSATION
	Stock-based compensation expense consists primarily of expenses for stock options and RSUs granted to employees and shares issued under the ESPP. The following table summarizes stock-based compensation expense (in thousands):
		Three months ended
		April 3,			March 28,
		2015			2014
	Stock-based compensation in:
	Cost of revenue	$	528		$	516
	Research and development expense	1,148			1,101
	Selling, general and administrative expense	2,458			2,190
	Total stock-based compensation in operating expense	3,606			3,291
	Total stock-based compensation	$	4,134		$	3,807
	The Company is required to estimate forfeitures at the time of grant and revise those estimates in subsequent periods if actual forfeitures differ from those estimates. The Company uses historical data to estimate pre-vesting option forfeitures and records stock-based compensation expense only for those awards that are expected to vest. All stock-based payment awards are amortized on a straight-line basis over the requisite service periods of the awards, which are generally the vesting periods.
	Stock Options
	The Company estimated the fair value of all employee stock options using a Black-Scholes valuation model with the following weighted average assumptions:
		Three months ended
		April 3,		March 28,
		2015		2014
	Expected term (years)	4.7		4.7
	Volatility	38	%	40	%
	Risk-free interest rate	1.6	%	1.7	%
	Expected dividends	0	%	0	%
	The expected term represents the weighted-average period that the stock options are expected to remain outstanding. The computation of the expected term was determined based on historical experience of similar awards, giving consideration to the contractual terms of the stock-based awards, vesting schedules and expectations of future employee behavior. The Company uses its historical volatility for a period equivalent to the expected term of the options to estimate the expected volatility. The risk-free interest rate that the Company uses in the Black-Scholes option valuation model is based on U.S. Treasury zero-coupon issues with remaining terms similar to the expected term. The Company has never declared or paid any cash dividends and does not plan to pay cash dividends in the foreseeable future, and, therefore, used an expected dividend yield of zero in the valuation model.
	The weighted-average fair value per share of options granted was $2.63 and $2.35 for the three months ended April 3, 2015 and March 28, 2014, respectively. The fair value of all stock options vested during the three months ended April 3, 2015 and March 28, 2014 were both $1.3 million. The total realized tax benefit attributable to stock options exercised during the three months ended April 3, 2015 and March 28, 2014, in jurisdictions where this expense is deductible for tax purposes, were $120,000 and $185,000, respectively.
	Restricted Stock Units
	The aggregate fair value of all RSUs issued during the three months ended April 3, 2015 and March 28, 2014 were $6.1 million and $5.4 million, respectively.
	Employee Stock Purchase Plan
	The value of the stock purchase rights under the ESPP consists of: (1) the 15% discount on the purchase of the stock; (2) 85% of the fair value of the call option; and (3) 15% of the fair value of the put option. The call option and put option were valued using the Black-Scholes option pricing model. The weighted average fair value of the Company's ESPP shares at purchase dates was estimated using the following weighted average assumptions during the three months ended April 3, 2015 and March 28, 2014:
		Purchase Period Ending
		June 30,		June 30,
		2015		2014
	Expected term (years)	0.49		0.5
	Volatility	35	%	29	%
	Risk-free interest rate	0.1	%	0.1	%
	Expected dividends	0	%	0	%
	Estimated weighted average fair value per share at purchase date	$1.74		$1.71
	The expected term represents the period of time from the beginning of the offering period to the purchase date. The Company uses its historical volatility for a period equivalent to the expected term of the options to estimate the expected volatility. The risk-free interest rate that the Company uses in the Black-Scholes option valuation model is based on U.S. Treasury zero-coupon issues with remaining terms similar to the expected term. The Company has never declared or paid any cash dividends and does not plan to pay cash dividends in the foreseeable future, and, therefore, used an expected dividend yield of zero in the valuation model.
	Unrecognized Stock-Based Compensation
	As of April 3, 2015, the Company had approximately $20.1 million of unrecognized stock-based compensation expense related to the unvested portion of its stock options and RSUs that is expected to be recognized over a weighted-average period of approximately 2.1 years.

Income_Taxes

Income Taxes	3 Months Ended
	Apr. 03, 2015
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES
	The Company reported the following operating results for the periods presented (in thousands):
		Three months ended
		April 3,			March 28,
		2015			2014
	Loss before income taxes	$	(2,943	)	$	(7,133	)
	Benefit from income taxes	(286		)	(1,723		)
	Effective income tax rate	9.7		%	24.2		%
	The Company's quarterly income taxes reflect an estimate of the corresponding fiscal year's annual effective tax rate and include, where applicable, adjustments for discrete tax items.
	In the three months ended April 3, 2015, the Company's effective income tax rate was 9.7%. The rate for the three months ended April 3, 2015 is lower than the U.S. federal statutory rate of 35% primarily because the loss before income taxes for three months ended April 3, 2015 included the loss on impairment of VJU investment (see Note 4, "Investments in Other Equity Securities") for which no tax benefit can be recognized. The effective tax rate for the three months ended April 3, 2015 excluding the loss on impairment of VJU would be approximately 65% and this is higher than the U.S. federal rate of 35% primarily due to an increase in the Company's U.S. current and non-current income tax payable as well as maintaining a full valuation allowance against all of the Company's U.S. deferred tax assets.
	In the three months ended March 28, 2014, the Company's effective rate was 24.2%, lower than the U.S. federal statutory rate of 35%, primarily due to favorable tax rates associated with certain earnings from operations in lower-tax jurisdictions, partially offset by the detriment from non-deductible stock-based compensation and non-deductible amortization of foreign intangibles, and various net discrete tax adjustments. For three months ended March 28, 2014, the discrete adjustments to the Company's tax benefit were primarily the accrual of interest on uncertain tax positions.
	The Company files U.S. federal and state, and foreign income tax returns in jurisdictions with varying statutes of limitations during which such tax returns may be audited and adjusted by the relevant tax authorities. The 2011 through 2014 tax years generally remain subject to examination by U.S. federal and most state tax authorities. In significant foreign jurisdictions, the 2006 through 2014 tax years generally remain subject to examination by their respective tax authorities. In the first quarter of 2015, the Israeli tax authority commenced an audit of a subsidiary of the Company for the 2012 and 2013 tax years. If, upon the conclusion of this audit, the ultimate determination of taxes owed in Israel is for an amount in excess of the tax provision the Company has recorded in the applicable period, the Company's overall tax expense, effective tax rate, operating results and cash flow could be materially and adversely impacted in the period of adjustment.
	The Company's operations in Switzerland are subject to a reduced tax rate under the Switzerland tax holiday which requires various thresholds of investment and employment in Switzerland. The Company has met these various thresholds and the Switzerland tax holiday is effective through the end of 2018.
	As of April 3, 2015, the total amount of gross unrecognized tax benefits, including interest and penalties, was approximately $16.3 million, that if recognized, would affect the Company's effective tax rate. The Company recognizes interest and penalties related to unrecognized tax positions in income tax expense. The Company had $0.6 million of gross interest and penalties accrued as of April 3, 2015. The Company will continue to review its tax positions and provide for, or reverse, unrecognized tax benefits as issues arise. As of April 3, 2015, the Company anticipates that the balance of gross unrecognized tax benefits will decrease up to approximately $1.0 million due to expiration of the applicable statues of limitations over the next twelve months.

Income_Loss_Per_Share

Income (Loss) Per Share	3 Months Ended
	Apr. 03, 2015
Earnings Per Share [Abstract]
Income (Loss) Per Share	INCOME (LOSS) PER SHARE
	The following table sets forth the computation of the basic and diluted net loss per share (in thousands, except per share amounts):
		Three months ended
		April 3,				March 28,
		2015				2014
	Numerator:
	Net loss	$	(2,657	)		$	(5,410	)
	Denominator:
	Weighted average number of common shares outstanding
	Basic and diluted	88,655				97,921
	Net loss per share:
	Basic and diluted	$	(0.03	)		$	(0.06	)
	The following table sets forth the potentially dilutive shares from stock options, RSUs and the ESPP, for the periods presented, that were excluded from the net loss per share computations because their effect was anti-dilutive (in thousands):
		Three months ended
		April 3,			March 28,
		2015			2014
	Potentially dilutive equity awards outstanding	9,641			11,072

Segment_Information

Segment Information	3 Months Ended
	Apr. 03, 2015
Segment Reporting [Abstract]
Segment Information	SEGMENT INFORMATION
	Operating segments are defined as components of an enterprise that engage in business activities for which separate financial information is available and evaluated by the Company's Chief Operating Decision Maker ( “CODM”), which for Harmonic is its Chief Executive Officer, in deciding how to allocate resources and assess performance. Prior to the fourth quarter of 2014, the Company operated its business in one reportable segment. In connection with the 2015 annual planning process, the Company changed its operating segments to align with how the CODM expected to evaluate the financial information used to allocate resources and assess performance of the Company. The new reporting structure consists of two operating segments: Video and Cable Edge. As a result, the segment information presented has been conformed to the new operating segments for all prior periods.
	The new operating segments were determined based on the nature of the products offered. The Video segment sells video processing and production and playout solutions and services worldwide to broadcast and media companies, streaming new media companies, cable operators, and satellite and telecommunications (telco) Pay-TV service providers. The Cable Edge segment sells cable edge solutions and related services to cable operators globally.
	The Company does not allocate amortization of intangibles, stock-based compensation, restructuring and asset impairment charges, and certain other non-recurring charges to the operating income for each segment because management does not include this information in the measurement of the performance of the operating segments. A measure of assets by segment is not applicable as segment assets are not included in the discrete financial information provided to the CODM.
	The following tables provide summary financial information by reportable segment (in thousands):
		Three months ended
		April 3, 2015			March 28, 2014
	Net revenue:
	Video	$	69,282		$	81,152
	Cable Edge	34,734			26,880
	Total consolidated net revenue	$	104,016		$	108,032
	Operating income (loss):
	Video	$	(90	)	$	2,435
	Cable Edge	6,188			1,044
	Total segment operating income	6,098			3,479
	Unallocated corporate expenses*	(44		)	(228		)
	Stock-based compensation	(4,134		)	(3,807		)
	Amortization of intangibles	(1,907		)	(6,666		)
	Income (loss) from operations	13			(7,222		)
	Non-operating income (expense)	(2,956		)	89
	Loss before income taxes	$	(2,943	)	$	(7,133	)
	*Unallocated corporate expenses include certain corporate-level operating expenses and charges such as restructuring and related charges.

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Apr. 03, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES
	Leases
	Future minimum lease payments under non-cancelable operating leases as of April 3, 2015, after giving effect to $131,000 of future sublease income, are as follows (in thousands):
	Years ending December 31,
	2015 (remaining 9 months)	$	7,591
	2016	8,788
	2017	8,067
	2018	7,933
	2019	7,885
	Thereafter	6,133
	Total	$	46,397
	Warranties
	The Company accrues for estimated warranty costs at the time of product shipment. Management periodically reviews the estimated fair value of its warranty liability and records adjustments based on the terms of warranties provided to customers, historical and anticipated warranty claims experience, and estimates of the timing and cost of warranty claims. Activity for the Company’s warranty accrual, which is included in accrued liabilities, is summarized below (in thousands):
		Three months ended
		April 3,			March 28,
		2015			2014
	Balance at beginning of period	$	4,242		$	3,606
	Accrual for current period warranties	1,595			1,749
	Warranty costs incurred	(1,746		)	(1,696		)
	Balance at end of period	$	4,091		$	3,659
	Purchase Commitments with Contract Manufacturers and Other Suppliers
	The Company relies on a limited number of contract manufacturers and suppliers to provide manufacturing services for a substantial majority of its products. In addition, some components, sub-assemblies and modules are obtained from a sole supplier or limited group of suppliers. During the normal course of business, in order to reduce manufacturing lead times and ensure adequate component supply, the Company enters into agreements with certain contract manufacturers and suppliers that allow them to procure inventory and services based upon criteria defined by the Company. The Company had approximately $22.6 million of non-cancelable purchase commitments with contract manufacturers and other suppliers as of April 3, 2015.
	Standby Letters of Credit
	As of April 3, 2015, the Company’s financial guarantees consisted of standby letters of credit outstanding, which were principally related to performance bonds and state requirements imposed on employers. The maximum amount of potential future payments under these arrangements was $0.4 million as of April 3, 2015.
	Indemnification
	Harmonic is obligated to indemnify its officers and the members of its Board of Directors pursuant to its bylaws and contractual indemnity agreements. Harmonic also indemnifies some of its suppliers and most of its customers for specified intellectual property matters pursuant to certain contractual arrangements, subject to certain limitations. The scope of these indemnities varies, but, in some instances, includes indemnification for damages and expenses (including reasonable attorneys’ fees). There have been no amounts accrued in respect of these indemnification provisions through April 3, 2015.
	Guarantees
	The Company has $0.4 million of guarantees in Israel as of April 3, 2015, with the majority relating to rent obligations for buildings used by its Israeli subsidiaries.
	Legal proceedings
	From time to time, the Company is involved in lawsuits as well as subject to various legal proceedings, claims, threats of litigation, and investigations in the ordinary course of business, including claims of alleged infringement of third-party patents and other intellectual property rights, commercial, employment, and other matters. The Company assesses potential liabilities in connection with each lawsuit and threatened lawsuits and accrues an estimated loss for these loss contingencies if both of the following conditions are met: information available prior to issuance of the financial statements indicates that it is probable that a liability has been incurred at the date of the financial statements and the amount of loss can be reasonably estimated. While certain matters to which the Company is a party specify the damages claimed, such claims may not represent reasonably possible losses. Given the inherent uncertainties of litigation, the ultimate outcome of these matters cannot be predicted at this time, nor can the amount of possible loss or range of loss, if any, be reasonably estimated.
	In October 2011, Avid Technology, Inc. (“Avid”) filed a complaint in the United States District Court for the District of Delaware alleging that the Company’s Media Grid product infringes two patents held by Avid. A jury trial on this complaint commenced on January 23, 2014 and, on February 4, 2014, the jury returned a unanimous verdict in favor of the Company, rejecting Avid's infringement allegations in their entirety.  On May 23, 2014, Avid filed a post-trial motion asking the court to set aside the jury’s verdict, and the judge issued an order on December 17, 2014, denying the motion. On January 5, 2015, Avid filed an appeal with respect to the jury’s verdict with the Federal Circuit, which was docketed on January 9, 2015, as Case No. 2015-1246. Avid filed its opening brief with respect to this appeal on March 24, 2015, and the Company filed its response brief on May 7, 2015.
	In June 2012, Avid served a subsequent complaint in the United States District Court for the District of Delaware alleging that the Company’s Spectrum product infringes one patent held by Avid. The complaint seeks injunctive relief and unspecified damages. In September 2013, the U.S. Patent Trial and Appeal Board (“PTAB”) authorized an inter partes review to be instituted as to claims 1-16 of the patent asserted in this second complaint. A hearing before the PTAB was conducted on May 20, 2014.  On July 10, 2014, the PTAB issued a decision finding claims 1 - 10 invalid and claims 11 - 16 not invalid.  The Company filed an appeal with respect to the PTAB’s decision on claims 11 - 16 on September 11, 2014. The appeal was docketed with the Federal Circuit on October 22, 2014, as Case No. 2015-1072, and the Company filed its opening brief with respect to this appeal on January 29, 2015. Avid and PTAB each filed a response brief on April 27, 2015.
	An unfavorable outcome on any litigation matter could require that the Company pay substantial damages, or, in connection with any intellectual property infringement claims, could require that the Company pay ongoing royalty payments or could prevent the Company from selling certain of its products. As a result, a settlement of, or an unfavorable outcome on, any of the matters referenced above or other litigation matters could have a material adverse effect on the Company’s business, operating results, financial position and cash flows.

Stockholders_Equity

Stockholders' Equity	3 Months Ended
	Apr. 03, 2015
Equity [Abstract]
Stockholders' Equity	STOCKHOLDERS’ EQUITY
	Accumulated Other Comprehensive Loss (“AOCI”)
	The components of accumulated other comprehensive loss, on an after-tax basis where applicable, were as follows (in thousands):
		Foreign Currency Translation Adjustments			Unrealized Gains (Losses) on Cash Flow Hedges			Unrealized Gains (Losses) on Available-for-Sale Investments			Total
	Balance as of December 31, 2014	$	(1,523	)	$	311		$	(768	)	$	(1,980	)
	Other comprehensive income (loss) before reclassifications	(984		)	(184		)	485			$	(683	)
	Amounts reclassified from AOCI	—			(49		)	—			(49		)
	Provision for income taxes	—			—			(4		)	(4		)
	Balance as of April 3, 2015	$	(2,507	)	$	78		(287		)	(2,716		)
	The effects of amounts reclassified from AOCI into the condensed consolidated statement of operations were as follows (in thousands):
		Three months ended
		3-Apr-15			28-Mar-14
	Gains on cash flow hedges from foreign currency contracts:
	Cost of revenue	$	7		$	—
	Operating expenses	42			—
	Total reclassifications from AOCI	$	49		$	—
	Common Stock Repurchases
	On April 24, 2012, the Company's Board of Directors (the “Board”) approved a stock repurchase program that provided for the repurchase of up to $25 million of our outstanding common stock. During 2013, the Board approved $195 million of increases to the program, increasing the aggregate authorized amount of the program to $220 million. On February 6, 2013, the Board approved a modification to the program that permits the Company to also repurchase its common stock pursuant to a plan that meets the requirements of Rule 10b5-1 under the Securities Exchange Act of 1934, as amended. On May 14, 2014, the Board approved an additional $80 million increase to the program, resulting in an aggregate authorized purchase of $300 million under the program and the repurchase period was extended through the end of 2016.
	As of April 3, 2015, the Company had purchased 37.9 million shares of common stock under this program at a weighted average price of $6.23 per share for an aggregate purchase price of $237.5 million, including $1.0 million of expenses. The remaining authorized amount for stock repurchases under this program was $63.5 million as of April 3, 2015. For additional information, see “Item 2 - Unregistered sales of equity securities and use of proceeds” of this Quarterly Report on Form 10-Q.

Basis_of_Presentation_and_Sign1

Basis of Presentation and Significant Accounting Policies (Policies)	3 Months Ended
	Apr. 03, 2015
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates
	The preparation of the condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from those estimates.
Significant Accounting Policies	The Company’s significant accounting policies are described in Note 2 to its audited Consolidated Financial Statements included in its 2014 Form 10-K. There have been no significant changes to these policies during the three months ended April 3, 2015.
Recent Accounting Pronouncements	RECENT ACCOUNTING PRONOUNCEMENTS
	On May 28, 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, “Revenue from Contracts with Customers”, requiring an entity to recognize the amount of revenue that reflects the consideration to which it expects to be entitled for the transfer of promised goods or services to customers. The updated standard will replace most existing revenue recognition guidance in U.S. GAAP when it becomes effective and permits the use of either the retrospective or cumulative effect transition method. Early adoption is not permitted. The updated standard becomes effective for the Company in the first quarter of fiscal 2017. In April 2015, the FASB announced a proposal to defer the effective date by one year, with early adoption on the original effective date permitted. The Company has not yet selected a transition method and it is currently evaluating the effect that the updated standard will have on its consolidated financial statements and related disclosures.
	On November 3, 2014, the FASB issued ASU No. 2014-16, “Derivatives and Hedging (Topic 815) - Determining Whether the Host Contract in a Hybrid Financial Instrument Issued in the Form of a Share is More Akin to Debt or to Equity”. ASU 2014-16 was issued to clarify how current U.S. GAAP should be interpreted in evaluating the economic characteristics and risk of a host contract in a hybrid financial instrument that is issued in the form of a share.  In addition, ASU 2014-16 was issued to clarify that in evaluating the nature of a host contract, an entity should assess the substance of the relevant terms and features (that is, the relative strength of the debt-like or equity-like terms and features given the facts and circumstances) when considering how to weight those terms and features. ASU 2014-16 is effective in the fiscal year beginning after December 15, 2015. Early adoption in an interim period is permitted. The Company is currently evaluating the impact of the adoption of ASU 2014-16 on its consolidated financial statements.
	On February 18, 2015, the FASB issued ASU No. 2015-02, “Consolidation (Topic 810) - Amendments to the Consolidation Analysis”, intended to improve targeted areas of consolidation guidance for all entities. ASU 2015-02 is effective in the fiscal year beginning after December 15, 2015. Early adoption in an interim period is permitted. The Company is currently evaluating the impact of the adoption of ASU 2015-02 on its consolidated financial statements.
	On April 15, 2015, the FASB issued ASU No. 2015-05, “Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40) - Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement”. ASU 2015-05 amends ASC 350-40 to provide customers with guidance on whether a cloud computing arrangement contains a software license to be accounted for as internal-use software. ASU No. 2015-05 is effective in the fiscal year beginning after December 15, 2015. Early adoption in an interim period is permitted. The Company is currently evaluating the impact of the adoption of ASU 2015-05 on its consolidated financial statements.
Impairment of Investments	Impairment of Short-term Investments
	The Company monitors its investment portfolio for impairment on a periodic basis. In the event that the carrying value of an investment exceeds its fair value and the decline in value is determined to be other-than-temporary, an impairment charge is recorded and a new cost basis for the investment is established. A decline of fair value below amortized costs of debt securities is considered other-than-temporary if the Company has the intent to sell the security or it is more likely than not that the Company will be required to sell the security before recovery of the entire amortized cost basis. At the present time, the Company does not intend to sell its investments that have unrealized losses in accumulated other comprehensive loss. In addition, the Company does not believe that it is more likely than not that it will be required to sell its investments that have unrealized losses in accumulated other comprehensive loss before the Company recovers the principal amounts invested. The Company believes that the unrealized losses are temporary and do not require an other-than-temporary impairment, based on its evaluation of available evidence as of April 3, 2015.
	As of April 3, 2015, there were no individual available-for-sale securities in a material unrealized loss position and the amount of unrealized losses on the total investment balance was insignificant.
Investments in Other Equity Securities	Each reporting period, the Company reviews all of its unconsolidated VIE investments to determine whether there are any reconsideration events that may result in the Company being a primary beneficiary of the unconsolidated VIE which would then require the Company to consolidate the VIE. The Company also reviews all of its cost-method investments in each reporting period to determine whether a significant event of change in circumstances has occurred that may have an adverse effect on the fair value of each investment.
Derivatives and Hedging Activities	Offsetting of Derivative Assets and Liabilities
	The Company recognizes all derivative instruments on a gross basis in the Condensed Consolidated Balance Sheet. However, the arrangements with its counterparties allows for net settlement, which are designed to reduce credit risk by permitting net settlement with the same counterparty. To further limit credit risk, the Company also enters into cash collateral security arrangements with the same counterparty.
	The Company uses forward contracts to manage exposures to foreign currency exchange rates. The Company's primary objective in holding derivative instruments is to reduce the volatility of earnings and cash flows associated with fluctuations in foreign currency exchange rates and the Company does not use derivative instruments for trading purposes. The use of derivative instruments expose the Company to credit risk to the extent that the counterparties may be unable to meet their contractual obligations, as such, the potential risk of loss with any one counterparty is closely monitored by the Company.
	Derivatives Designated as Hedging Instruments (Cash Flow Hedges)
	Beginning in December 2014, the Company entered into forward currency contracts to hedge forecasted operating expenses and service costs related to employee salaries and benefits denominated in Israeli shekels (“ILS”) for its subsidiaries in Israel. These ILS forward contacts mature generally within twelve months and are designated as cash flow hedges. For derivatives that are designated as hedges of forecasted foreign currency denominated operating expenses and service costs, the Company assesses effectiveness based on changes in spot currency exchange rates. Changes in spot rates on the derivative are recorded as a component of “Accumulated other comprehensive income (loss)” (“OCI”) in the Condensed Consolidated Balance Sheet until such time as the hedged transaction impacts earnings. The change in fair value of the forward points, which reflects the interest rate differential between the two countries on the derivative, is excluded from the effectiveness assessment. Gains or losses on the derivative representing either hedge ineffectiveness or hedge components excluded from the assessment of effectiveness are recognized in current earnings.
	Derivatives Not Designated as Hedging Instruments (Balance Sheet Hedges)
	Balance sheet hedges consist of foreign currency forward contracts, mature generally within three months, are carried at fair value and they are used to minimize the short-term impact of foreign currency exchange rate fluctuation on cash and certain trade and inter-company receivables and payables. Changes in the fair value of these foreign currency forward contracts are recognized in “Other income (expense), net” in the Condensed Consolidated Statement of Operations and are largely offset by the changes in the fair value of the assets or liabilities being hedged.
Fair Value of Financial Instruments	The applicable accounting guidance establishes a framework for measuring fair value and requires disclosure about the fair value measurements of assets and liabilities. This guidance requires the Company to classify and disclose assets and liabilities measured at fair value on a recurring basis, as well as fair value measurements of assets and liabilities measured on a nonrecurring basis in periods subsequent to initial measurement, in a three-tier fair value hierarchy as described below.
	The guidance defines fair value as the exchange price that would be received for an asset or paid to transfer a liability, in the principal or most advantageous market for the asset or liability, in an orderly transaction between market participants on the measurement date.
	Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The guidance describes three levels of inputs that may be used to measure fair value:
	•	Level 1 — Observable inputs that reflect quoted prices for identical assets or liabilities in active markets.
	•	Level 2 — Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. The Company primarily uses broker quotes for valuation of its short-term investments. The forward exchange contracts are classified as Level 2 because they are valued using quoted market prices and other observable data for similar instruments in an active market.
	•	Level 3 — Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.
	The Company uses the market approach to measure fair value for its financial assets and liabilities. The market approach uses prices and other relevant information generated by market transactions involving identical or comparable assets or liabilities. During the three months ended April 3, 2015, there were no nonrecurring fair value measurements of assets and liabilities subsequent to initial recognition.
Share-based Compensation Expense	Stock Options
	The Company estimated the fair value of all employee stock options using a Black-Scholes valuation model with the following weighted average assumptions:
		Three months ended
		April 3,		March 28,
		2015		2014
	Expected term (years)	4.7		4.7
	Volatility	38	%	40	%
	Risk-free interest rate	1.6	%	1.7	%
	Expected dividends	0	%	0	%
	The expected term represents the weighted-average period that the stock options are expected to remain outstanding. The computation of the expected term was determined based on historical experience of similar awards, giving consideration to the contractual terms of the stock-based awards, vesting schedules and expectations of future employee behavior. The Company uses its historical volatility for a period equivalent to the expected term of the options to estimate the expected volatility. The risk-free interest rate that the Company uses in the Black-Scholes option valuation model is based on U.S. Treasury zero-coupon issues with remaining terms similar to the expected term. The Company has never declared or paid any cash dividends and does not plan to pay cash dividends in the foreseeable future, and, therefore, used an expected dividend yield of zero in the valuation model.
	The weighted-average fair value per share of options granted was $2.63 and $2.35 for the three months ended April 3, 2015 and March 28, 2014, respectively. The fair value of all stock options vested during the three months ended April 3, 2015 and March 28, 2014 were both $1.3 million. The total realized tax benefit attributable to stock options exercised during the three months ended April 3, 2015 and March 28, 2014, in jurisdictions where this expense is deductible for tax purposes, were $120,000 and $185,000, respectively.
	Restricted Stock Units
	The aggregate fair value of all RSUs issued during the three months ended April 3, 2015 and March 28, 2014 were $6.1 million and $5.4 million, respectively.
	Employee Stock Purchase Plan
	The value of the stock purchase rights under the ESPP consists of: (1) the 15% discount on the purchase of the stock; (2) 85% of the fair value of the call option; and (3) 15% of the fair value of the put option. The call option and put option were valued using the Black-Scholes option pricing model. The weighted average fair value of the Company's ESPP shares at purchase dates was estimated using the following weighted average assumptions during the three months ended April 3, 2015 and March 28, 2014:
		Purchase Period Ending
		June 30,		June 30,
		2015		2014
	Expected term (years)	0.49		0.5
	Volatility	35	%	29	%
	Risk-free interest rate	0.1	%	0.1	%
	Expected dividends	0	%	0	%
	Estimated weighted average fair value per share at purchase date	$1.74		$1.71
	The expected term represents the period of time from the beginning of the offering period to the purchase date. The Company uses its historical volatility for a period equivalent to the expected term of the options to estimate the expected volatility. The risk-free interest rate that the Company uses in the Black-Scholes option valuation model is based on U.S. Treasury zero-coupon issues with remaining terms similar to the expected term. The Company has never declared or paid any cash dividends and does not plan to pay cash dividends in the foreseeable future, and, therefore, used an expected dividend yield of zero in the valuation model.
	Unrecognized Stock-Based Compensation
	As of April 3, 2015, the Company had approximately $20.1 million of unrecognized stock-based compensation expense related to the unvested portion of its stock options and RSUs that is expected to be recognized over a weighted-average period of approximately 2.1 years.
Income Tax	As of April 3, 2015, the total amount of gross unrecognized tax benefits, including interest and penalties, was approximately $16.3 million, that if recognized, would affect the Company's effective tax rate. The Company recognizes interest and penalties related to unrecognized tax positions in income tax expense. The Company had $0.6 million of gross interest and penalties accrued as of April 3, 2015. The Company will continue to review its tax positions and provide for, or reverse, unrecognized tax benefits as issues arise. As of April 3, 2015, the Company anticipates that the balance of gross unrecognized tax benefits will decrease up to approximately $1.0 million due to expiration of the applicable statues of limitations over the next twelve months.
Warranties and Indemnification	The Company accrues for estimated warranty costs at the time of product shipment. Management periodically reviews the estimated fair value of its warranty liability and records adjustments based on the terms of warranties provided to customers, historical and anticipated warranty claims experience, and estimates of the timing and cost of warranty claims.
	Harmonic is obligated to indemnify its officers and the members of its Board of Directors pursuant to its bylaws and contractual indemnity agreements. Harmonic also indemnifies some of its suppliers and most of its customers for specified intellectual property matters pursuant to certain contractual arrangements, subject to certain limitations. The scope of these indemnities varies, but, in some instances, includes indemnification for damages and expenses (including reasonable attorneys’ fees).
Segment Information	Operating segments are defined as components of an enterprise that engage in business activities for which separate financial information is available and evaluated by the Company's Chief Operating Decision Maker ( “CODM”), which for Harmonic is its Chief Executive Officer, in deciding how to allocate resources and assess performance. Prior to the fourth quarter of 2014, the Company operated its business in one reportable segment. In connection with the 2015 annual planning process, the Company changed its operating segments to align with how the CODM expected to evaluate the financial information used to allocate resources and assess performance of the Company. The new reporting structure consists of two operating segments: Video and Cable Edge. As a result, the segment information presented has been conformed to the new operating segments for all prior periods.
	The new operating segments were determined based on the nature of the products offered. The Video segment sells video processing and production and playout solutions and services worldwide to broadcast and media companies, streaming new media companies, cable operators, and satellite and telecommunications (telco) Pay-TV service providers. The Cable Edge segment sells cable edge solutions and related services to cable operators globally.
	The Company does not allocate amortization of intangibles, stock-based compensation, restructuring and asset impairment charges, and certain other non-recurring charges to the operating income for each segment because management does not include this information in the measurement of the performance of the operating segments. A measure of assets by segment is not applicable as segment assets are not included in the discrete financial information provided to the CODM.

ShortTerm_Investments_Tables

Short-Term Investments (Tables)	3 Months Ended
	Apr. 03, 2015
Cash and Cash Equivalents [Abstract]
Summary of Short-Term Investments	The following table summarizes the Company’s short-term investments (in thousands):
		Amortized		Gross		Gross			Estimated
		Cost		Unrealized		Unrealized			Fair Value
				Gains		Losses
	As of April 3, 2015
	State, municipal and local government agencies bonds	$	11,228	$	10	$	—		$	11,238
	Corporate bonds	10,969		1		(5		)	10,965
	Total short-term investments	$	22,197	$	11	$	(5	)	$	22,203
	As of December 31, 2014
	State, municipal and local government agencies bonds	$	13,946	$	16	$	(1	)	$	13,961
	Corporate bonds	17,899		3		(16		)	17,886
	Total short-term investments	$	31,845	$	19	$	(17	)	$	31,847
Maturities of Short-Term Investments	The following table summarizes the maturities of the Company’s short-term investments (in thousands):
		3-Apr-15		31-Dec-14
	Less than one year	$	22,203	$	30,946
	Due in 1 - 2 years	—		901
	Total short-term investments	$	22,203	$	31,847

Investments_in_Other_Equity_Se1

Investments in Other Equity Securities Schedule of Cost Method Investments (Tables)	3 Months Ended
	Apr. 03, 2015
Investments, All Other Investments [Abstract]
Cost Method Investments	The following table presents the carrying values and maximum exposure of the unconsolidated VIEs as of April 3, 2015 (in thousands):
		Carrying Value		Maximum exposure to loss(1)
	VJU	—		—
	EDC(2)	3,593		3,593
	Total	$	3,593	$	3,593

Derivative_and_Hedging_Activit

Derivative and Hedging Activities (Tables)	3 Months Ended
	Apr. 03, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments gain and losses by Statement of Operations locations	The locations and amounts of designated and non-designated derivative instruments' gains and losses reported in the Company's Condensed Consolidated Statements of Operations were as follows (in thousands):
				Three months ended
		Financial Statement Location		3-Apr-15				28-Mar-14
	Derivatives Designated as Hedging instruments:
	Gains in accumulated OCI on derivatives (effective portion)	Accumulated OCI		$	184			$	—
	Gains reclassified from accumulated OCI into income (effective portion)	Cost of Revenue		$	7			$	—
		Operating Expense		42				—
		Total		$	49			$	—
	Loss recognized in income on derivatives (ineffectiveness portion and amount excluded from effectiveness testing)	Other income (expense), net		$	(42	)		$	—
	Derivatives Not Designated as Hedging instruments:
	Gains (losses) recognized in income	Other income (expense), net		$	252			$	(177	)
Schedule of Notional Amounts of Outstanding Derivative Positions	The U.S. dollar equivalents of all outstanding notional amounts of foreign currency forward contracts are summarized as follows (in thousands):
		3-Apr-15				31-Dec-14
	Derivatives designated as cash flow hedges:
	Purchase	$	12,728			$	16,903
	Derivatives not designated as hedging instruments:
	Purchase	$	6,585			$	1,043
	Sell	$	9,069			$	4,925
Schedule of Derivatives Instruments Balance Sheet Location	The locations and fair value amounts of the Company's derivative instruments reported in its Condensed Consolidated Balance Sheets are as follows (in thousands):
				Asset Derivatives									Derivative Liabilities
		Balance Sheet Location		April 3, 2015				December 31, 2014			Balance Sheet Location		April 3, 2015			December 31, 2014
	Derivatives designated as hedging instruments:
	Foreign currency contracts	Prepaid expenses and other current assets		$	57			$	329		Accrued Liabilities		$	—		$	—
				$	57			$	329				$	—		$	—
	Derivatives not designated as hedging instruments:
	Foreign currency contracts	Prepaid expenses and other current assets		$	91			$	12		Accrued Liabilities		$	18		$	7
				$	91			$	12				$	18		$	7
	Total derivatives			$	148			$	341				$	18		$	7
Changes in fair values of non-designated foreign currency forward contracts	As of April 3, 2015, information related to the offsetting arrangements was as follows (in thousands):
												Gross Amounts of Derivatives Not Offset in the Condensed Consolidated Balance Sheets
		Gross Amounts of Derivatives				Gross Amounts of Derivatives Offset in the Condensed Consolidated Balance sheets			Net Amounts of Derivatives Presented in the Condensed Consolidated Balance Sheets			Financial Instrument			Cash Collateral Pledged			Net Amount
	Derivative Assets	$	148			—			$	148		$	(18	)	—			$	130
	Derivative Liabilities	$	18			—			$	18		$	(18	)	—			$	—

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Apr. 03, 2015
Fair Value Disclosures [Abstract]
Financial Assets and Liabilities Measured at Fair Value Based on Three-Tier Fair Value Hierarchy	The following table sets forth the fair value of the Company’s financial assets and liabilities measured at fair value based on the three-tier fair value hierarchy (in thousands):
		Level 1		Level 2		Level 3		Total
	As of April 3, 2015
	Cash equivalents
	Money market funds	$	32,795	$	—	$	—	$	32,795
	Short-term investments
	State, municipal and local government agencies bonds	—		11,238		—		11,238
	Corporate bonds	—		10,965		—		10,965
	Prepaids and other current assets
	Derivative assets	—		148		—		148
	Other assets
	Long-term investment	3,082		—		—		3,082
	Total assets measured and recorded at fair value	$	35,877	$	22,351	$	—	$	58,228
	Accrued liabilities
	Derivative liabilities	$	—	$	18	$	—	$	18
	Total liabilities measured and recorded at fair value	$	—	$	18	$	—	$	18
		Level 1		Level 2		Level 3		Total
	As of December 31, 2014
	Cash equivalents
	Money market funds	$	23,121	$	—	$	—	$	23,121
	Short-term investments
	State, municipal and local government agencies bonds	—		13,961		—		13,961
	Corporate bonds	—		17,886		—		17,886
	Prepaids and other current assets
	Derivative assets	—		341		—		341
	Other assets
	Long-term investment	2,606		—		—		2,606
	Total assets measured and recorded at fair value	$	25,727	$	32,188	$	—	$	57,915
	Accrued liabilities
	Derivative liabilities	$	—	$	7	$	—	$	7
	Total liabilities measured and recorded at fair value	$	—	$	7	$	—	$	7

Balance_Sheet_Components_Table

Balance Sheet Components (Tables)	3 Months Ended
	Apr. 03, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accounts Receivable, Net
		3-Apr-15			31-Dec-14
	Accounts receivable, net:
	Accounts receivable	$	80,974		$	81,201
	Less: allowances for doubtful accounts, returns and discounts	(5,110		)	(7,057		)
	Total	$	75,864		$	74,144
Prepaid, and Other Current Assets
	Prepaid expenses and other current assets:
	Prepaid inventories to contract manufacturer(1)	$	14,200		$	—
	Prepaid software license to Vislink(2)	1,090			1,233
	Other Prepayments	9,953			9,713
	Deferred cost of revenue	3,364			2,524
	Income tax receivable	1,664			2,316
	Other	255			1,753
		$	30,526		$	17,539
Inventories
	Inventories:
	Raw materials	$	1,844		$	1,422
	Work-in-process	1,439			1,255
	Finished goods	28,235			30,070
	Total	$	31,518		$	32,747
Property and Equipment, Net
	Property and equipment, net:
	Furniture and fixtures	$	7,690		$	7,691
	Machinery and equipment	116,895			116,031
	Leasehold improvements	9,550			8,140
	Property and equipment, gross	134,135			131,862
	Less: accumulated depreciation and amortization	(106,995		)	(104,641		)
	Total	$	27,140		$	27,221

Goodwill_and_Identified_Intang1

Goodwill and Identified Intangible Assets (Tables)	3 Months Ended
	Apr. 03, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Changes in Carrying Amount of Goodwill	The following table presents goodwill by reportable segments (in thousands):
		Video				Cable Edge				Total
	As of December 31, 2014	$	136,975			$	60,909			$	197,884
	Foreign currency translation adjustment	(75		)		(33		)		(108		)
	As of April 3, 2015	$	136,900			$	60,876			$	197,776
Summary of Goodwill and Identified Intangible Assets	The following is a summary of identifiable intangible assets (in thousands):
				3-Apr-15										31-Dec-14
		Range of Useful Lives		Gross Carrying				Accumulated				Net Carrying		Gross Carrying		Accumulated			Net Carrying
				Amount				Amortization				Amount		Amount		Amortization			Amount
	Identifiable intangibles:
	Developed core technology	4-6 years		$	136,145			$	(135,887	)		$	258	$	136,145	$	(135,426	)	$	719
	Customer relationships/contracts	5-6 years		67,098				(60,001		)		7,097		67,098		(58,784		)	8,314
	Maintenance agreements and related relationships	6-7 years		7,100				(5,763		)		1,337		7,100		(5,534		)	1,566
	Total identifiable intangibles			$	210,343			$	(201,651	)		$	8,692	$	210,343	$	(199,744	)	$	10,599
Amortization Expense for Identifiable Purchased Intangible Assets	Amortization expense for the identifiable purchased intangible assets for the three months ended April 3, 2015 and March 28, 2014 was allocated as follows (in thousands):
			Three months ended
			April 3,				March 28,
			2015				2014
	Included in cost of revenue		$	461			$	4,716
	Included in operating expenses		1,446				1,950
	Total amortization expense		$	1,907			$	6,666
Estimated Future Amortization Expense of Purchased Intangible Assets	The estimated future amortization expense of purchased intangible assets with definite lives is as follows (in thousands):
		Cost of Revenue				Operating				Total
						Expenses
	Year ended December 31,
	2015 (remaining 9 months)	$	258			$	4,337			$	4,595
	2016	—				4,097				4,097
	Total future amortization expense	$	258			$	8,434			$	8,692

Restructuring_and_Related_Char1

Restructuring and Related Charges (Tables)	3 Months Ended
	Apr. 03, 2015
Restructuring Cost and Reserve [Line Items]
Summary of restructuring activities	The following table summarizes the restructuring and related charges (in thousands):
		Three months ended
		April 3,			March 28,
		2015			2014
	Restructuring and related charges in:
	Product cost of revenue	$	—		$	79
	Operating expenses-Restructuring and related charges	44			149
		$	44		$	228
Harmonic Two Thousand And Fifteen Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Schedule of Restructuring Reserve by Type of Cost	The following table summarizes the activity in the Harmonic 2015 restructuring accrual during the three months ended April 3, 2015 (in thousands):
		Severance and benefits			Other charges			Total
	Balance at December 31, 2014	$	305		$	17		$	322
	Restructuring charges	56			—			56
	Adjustments to restructuring provisions	(5		)	(7		)	(12		)
	Cash payments	(312		)	(9		)	(321		)
	Non-cash write-offs	—			2			2
	Balance at April 3, 2015	$	44		$	3		$	47

Employee_Benefit_Plans_Tables

Employee Benefit Plans (Tables)	3 Months Ended
	Apr. 03, 2015
Postemployment Benefits [Abstract]
Summary of Company's Stock Option and Restricted Stock Unit Activity	The following table summarizes the Company’s stock option and RSU unit activity during the three months ended April 3, 2015 (in thousands, except per share amounts):
				Stock Options Outstanding						Restricted Stock Units Outstanding
		Shares		Number			Weighted			Number		Weighted
		Available for		of			Average			of		Average
		Grant		Shares			Exercise Price			Units		Grant
												Date Fair
												Value
	Balance at December 31, 2014	7,480		7,255			$	6.65		2,241		$	6.4
	Authorized			—			—			—		—
	Granted	(3,037	)	1,049			7.58			1,325		7.57
	Options exercised	—		(617	)		5.49			—		—
	Shares released	—		—			—			(925	)	6.56
	Forfeited or cancelled	283		(172	)		6.86			(73	)	6.23
	Balance at April 3, 2015	4,726		7,515			$	6.87		2,568		$	7.01
Summary of Stock Options Outstanding	The following table summarizes information about stock options outstanding as of April 3, 2015 (in thousands, except per share amounts):
		Number		Weighted				Weighted	Aggregate
		of		Average				Average	Intrinsic
		Shares		Exercise				Remaining	Value
				Price				Contractual
								Term (Years)
	Vested and expected to vest	7,126		$	6.87			3.7	$	6,331
	Exercisable	4,694		6.94				2.5	4,571
Summary of Restricted Stock Units Outstanding	The following table summarizes information about RSUs outstanding as of April 3, 2015 (in thousands, except per share amounts):
		Number of		Weighted		Aggregate
		Shares		Average		Fair
		Underlying		Remaining		Value
		Restricted		Vesting
		Stock		Period
		Units		(Years)
	Vested and expected to vest	2,359		0.8		$	17,407

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	3 Months Ended
	Apr. 03, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Stock-Based Compensation Expense	The following table summarizes stock-based compensation expense (in thousands):
		Three months ended
		April 3,			March 28,
		2015			2014
	Stock-based compensation in:
	Cost of revenue	$	528		$	516
	Research and development expense	1,148			1,101
	Selling, general and administrative expense	2,458			2,190
	Total stock-based compensation in operating expense	3,606			3,291
	Total stock-based compensation	$	4,134		$	3,807
Valuation Assumptions for Stock Options	The Company estimated the fair value of all employee stock options using a Black-Scholes valuation model with the following weighted average assumptions:
		Three months ended
		April 3,		March 28,
		2015		2014
	Expected term (years)	4.7		4.7
	Volatility	38	%	40	%
	Risk-free interest rate	1.6	%	1.7	%
	Expected dividends	0	%	0	%
Employee Stock Purchase Plan	The call option and put option were valued using the Black-Scholes option pricing model. The weighted average fair value of the Company's ESPP shares at purchase dates was estimated using the following weighted average assumptions during the three months ended April 3, 2015 and March 28, 2014:
		Purchase Period Ending
		June 30,		June 30,
		2015		2014
	Expected term (years)	0.49		0.5
	Volatility	35	%	29	%
	Risk-free interest rate	0.1	%	0.1	%
	Expected dividends	0	%	0	%
	Estimated weighted average fair value per share at purchase date	$1.74		$1.71

Income_Taxes_Tables

Income Taxes (Tables)	3 Months Ended
	Apr. 03, 2015
Income Tax Disclosure [Abstract]
Schedule of income before income tax	The Company reported the following operating results for the periods presented (in thousands):
		Three months ended
		April 3,			March 28,
		2015			2014
	Loss before income taxes	$	(2,943	)	$	(7,133	)
	Benefit from income taxes	(286		)	(1,723		)
	Effective income tax rate	9.7		%	24.2		%

Income_Loss_Per_Share_Tables

Income (Loss) Per Share (Tables)	3 Months Ended
	Apr. 03, 2015
Earnings Per Share [Abstract]
Numerators and Denominators of Basic and Diluted Net Income (Loss) Per Share Computations	The following table sets forth the computation of the basic and diluted net loss per share (in thousands, except per share amounts):
		Three months ended
		April 3,				March 28,
		2015				2014
	Numerator:
	Net loss	$	(2,657	)		$	(5,410	)
	Denominator:
	Weighted average number of common shares outstanding
	Basic and diluted	88,655				97,921
	Net loss per share:
	Basic and diluted	$	(0.03	)		$	(0.06	)
Anti-dilutive Securities	The following table sets forth the potentially dilutive shares from stock options, RSUs and the ESPP, for the periods presented, that were excluded from the net loss per share computations because their effect was anti-dilutive (in thousands):
		Three months ended
		April 3,			March 28,
		2015			2014
	Potentially dilutive equity awards outstanding	9,641			11,072

Segment_Information_Tables

Segment Information (Tables)	3 Months Ended
	Apr. 03, 2015
Segment Reporting [Abstract]
Segment Reporting Information, by Segment	The following tables provide summary financial information by reportable segment (in thousands):
		Three months ended
		April 3, 2015			March 28, 2014
	Net revenue:
	Video	$	69,282		$	81,152
	Cable Edge	34,734			26,880
	Total consolidated net revenue	$	104,016		$	108,032
	Operating income (loss):
	Video	$	(90	)	$	2,435
	Cable Edge	6,188			1,044
	Total segment operating income	6,098			3,479
	Unallocated corporate expenses*	(44		)	(228		)
	Stock-based compensation	(4,134		)	(3,807		)
	Amortization of intangibles	(1,907		)	(6,666		)
	Income (loss) from operations	13			(7,222		)
	Non-operating income (expense)	(2,956		)	89
	Loss before income taxes	$	(2,943	)	$	(7,133	)
	*Unallocated corporate expenses include certain corporate-level operating expenses and charges such as restructuring and related charges.

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	3 Months Ended
	Apr. 03, 2015
Commitments and Contingencies Disclosure [Abstract]
Future Minimum Lease Payments Under Non-cancelable Operating Leases	Future minimum lease payments under non-cancelable operating leases as of April 3, 2015, after giving effect to $131,000 of future sublease income, are as follows (in thousands):
	Years ending December 31,
	2015 (remaining 9 months)	$	7,591
	2016	8,788
	2017	8,067
	2018	7,933
	2019	7,885
	Thereafter	6,133
	Total	$	46,397
Summary of Warranty Accrual Included in Accrued Liabilities	Activity for the Company’s warranty accrual, which is included in accrued liabilities, is summarized below (in thousands):
		Three months ended
		April 3,			March 28,
		2015			2014
	Balance at beginning of period	$	4,242		$	3,606
	Accrual for current period warranties	1,595			1,749
	Warranty costs incurred	(1,746		)	(1,696		)
	Balance at end of period	$	4,091		$	3,659

Stockholders_Equity_Tables

Stockholders' Equity (Tables)	3 Months Ended
	Apr. 03, 2015
Equity [Abstract]
Components of Accumulated Other Comprehensive Loss	The components of accumulated other comprehensive loss, on an after-tax basis where applicable, were as follows (in thousands):
		Foreign Currency Translation Adjustments			Unrealized Gains (Losses) on Cash Flow Hedges			Unrealized Gains (Losses) on Available-for-Sale Investments			Total
	Balance as of December 31, 2014	$	(1,523	)	$	311		$	(768	)	$	(1,980	)
	Other comprehensive income (loss) before reclassifications	(984		)	(184		)	485			$	(683	)
	Amounts reclassified from AOCI	—			(49		)	—			(49		)
	Provision for income taxes	—			—			(4		)	(4		)
	Balance as of April 3, 2015	$	(2,507	)	$	78		(287		)	(2,716		)
	The effects of amounts reclassified from AOCI into the condensed consolidated statement of operations were as follows (in thousands):
		Three months ended
		3-Apr-15			28-Mar-14
	Gains on cash flow hedges from foreign currency contracts:
	Cost of revenue	$	7		$	—
	Operating expenses	42			—
	Total reclassifications from AOCI	$	49		$	—

ShortTerm_Investments_Summary_

Short-Term Investments - Summary of Short-Term Investments (Detail) (USD $)	Apr. 03, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	$22,197	$31,845
Gross Unrealized Gains	11	19
Gross Unrealized Losses	-5	-17
Total short-term investments, Estimated Fair Value	22,203	31,847
State, municipal and local government agencies bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	11,228	13,946
Gross Unrealized Gains	10	16
Gross Unrealized Losses	0	-1
Total short-term investments, Estimated Fair Value	11,238	13,961
Corporate bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	10,969	17,899
Gross Unrealized Gains	1	3
Gross Unrealized Losses	-5	-16
Total short-term investments, Estimated Fair Value	$10,965	$17,886

ShortTerm_Investments_Maturiti

Short-Term Investments - Maturities of Short-Term Investments (Detail) (USD $)	Apr. 03, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Investments, Debt and Equity Securities [Abstract]
Less than one year	$22,203	$30,946
Due in 1 - 2 years	0	901
Total short-term investments, Estimated Fair Value	$22,203	$31,847

ShortTerm_Investments_Addition

Short-Term Investments - Additional Information (Detail) (USD $)	Apr. 03, 2015	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Cost Method Investments	$6,700,000	$8,600,000
Available-for-sale securities in a material unrealized loss position	$0

Investments_in_Other_Equity_Se2

Investments in Other Equity Securities Investments in Other Equity Securities (Details) (USD $)	3 Months Ended			1 Months Ended	12 Months Ended
	Apr. 03, 2015		Mar. 28, 2014	Sep. 30, 2014	Dec. 31, 2014	Sep. 26, 2014	Sep. 02, 2014	Oct. 22, 2014
Schedule of Cost-method Investments [Line Items]
Prepaid expenses and other current assets	$30,526,000				$17,539,000
Cost Method Investments Carrying Value	6,700,000				8,600,000
Loss on impairment of long-term investment	2,505,000		0
Research and development	22,329,000		23,888,000
VJU GmbH [Member]
Schedule of Cost-method Investments [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent						19.80%
Cost Method Investments Original Cost						2,500,000
Loss on impairment of long-term investment	2,500,000
Research and development				100,000
Vislink plc [Member]
Schedule of Cost-method Investments [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent							3.30%
Cost Method Investments Original Cost							3,300,000
Prepaid expenses and other current assets	1,100,000						3,300,000
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	3,300,000
Cost Method Investments Carrying Value	3,100,000				2,600,000
Unrealized Loss on Cost Method Investments	200,000				700,000
Loss on impairment of long-term investment	0
EDC [Member]
Schedule of Cost-method Investments [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent								18.40%
Cost Method Investments Original Cost								3,500,000
Variable Interest Entity, Not Primary Beneficiary [Member]
Schedule of Cost-method Investments [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	3,593,000	[1]
Cost Method Investments Carrying Value	3,593,000
Variable Interest Entity, Not Primary Beneficiary [Member] | VJU GmbH [Member]
Schedule of Cost-method Investments [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	0	[1]
Variable Interest Entity, Not Primary Beneficiary [Member] | EDC [Member]
Schedule of Cost-method Investments [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	3,593,000	[1],[2]
Cost Method Investments Carrying Value	3,593,000	[2]
Business Acquisition, Transaction Costs	100,000	[2]
Cost-method Investments [Member] | Variable Interest Entity, Not Primary Beneficiary [Member] | VJU GmbH [Member]
Schedule of Cost-method Investments [Line Items]
Cost Method Investments Carrying Value	$0
[1]	The Company did not provide financial support to any of its unconsolidated VIEs and as of April 3, 2015, there were no explicit arrangements or implicit variable interests that could require the Company to provide financial support to any of its unconsolidated VIEs.
[2]	maximum exposure to loss with respect to EDC as of April 3, 2015 was limited to a total investment cost of $3.6 million, including $0.1 million of transaction costs.

Derivative_and_Hedgiing_Activi1

Derivative and Hedgiing Activities Derivatives and Hedging Activities - Additional Information (Details) (USD $)	12 Months Ended	3 Months Ended
	Dec. 31, 2014	Apr. 03, 2015	Mar. 28, 2014
Derivative [Line Items]
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax	311,000	$78,000
Designated as Hedging Instrument [Member] | Forward Contracts [Member]
Derivative [Line Items]
Derivative, Term of Contract	12 months
Not Designated as Hedging Instrument [Member] | Forward Contracts [Member]
Derivative [Line Items]
Derivative, Term of Contract	3 months
Other Comprehensive Income (Loss) [Member]
Derivative [Line Items]
Net unrealized gains in AOCI		184,000	0
Operating Expense [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Derivative [Line Items]
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax		$78,000

Derivative_and_Hedgiing_Activi2

Derivative and Hedgiing Activities Derivative and Hedging Activities gain losses in Statement of Operations (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Apr. 03, 2015	Mar. 28, 2014
Derivatives, Fair Value [Line Items]
Gains reclassified from accumulated OCI into income (effective portion)	$49	$0
Other Comprehensive Income (Loss) [Member]
Derivatives, Fair Value [Line Items]
Gains in accumulated OCI on derivatives (effective portion)	184	0
Product cost of revenue [Member]
Derivatives, Fair Value [Line Items]
Gains reclassified from accumulated OCI into income (effective portion)	7	0
Operating Expense [Member]
Derivatives, Fair Value [Line Items]
Gains reclassified from accumulated OCI into income (effective portion)	42	0
Other Nonoperating Income (Expense) [Member]
Derivatives, Fair Value [Line Items]
Loss recognized in income on derivatives (ineffectiveness portion and amount excluded from effectiveness testing)	-42	0
Other Nonoperating Income (Expense) [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Gains (losses) recognized in income	$252	($177)

Derivative_and_Hedgiing_Activi3

Derivative and Hedgiing Activities Derivatives and Hedging Activities Notional Amounts (Details) (Foreign Exchange Forward [Member], USD $)	Apr. 03, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Long [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Asset, Notional Amount	$12,728	$16,903
Long [Member] | Not Designated as Hedging Instrument [Member] | Fair Value Hedging [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Asset, Notional Amount	6,585	1,043
Short [Member] | Not Designated as Hedging Instrument [Member] | Fair Value Hedging [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Liability, Notional Amount	$9,069	$4,925

Derivative_and_Hedgiing_Activi4

Derivative and Hedgiing Activities Derivatives and Hedging Activities Assets Liabilities Balance Sheet Location (Details) (Foreign Exchange Contract [Member], USD $)	Apr. 03, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Derivatives, Fair Value [Line Items]
Derivative Asset, Current	$148	$341
Derivative Liability, Current	18	7
Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Current	57	329
Derivative Liability, Current	0	0
Designated as Hedging Instrument [Member] | Prepaid Expenses and Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Current	57	329
Designated as Hedging Instrument [Member] | Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Current	0	0
Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Current	91	12
Derivative Liability, Current	18	7
Not Designated as Hedging Instrument [Member] | Prepaid Expenses and Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Current	91	12
Not Designated as Hedging Instrument [Member] | Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Current	$18	$7

Derivative_and_Hedgiing_Activi5

Derivative and Hedgiing Activities Derivatives and Hedging Activities Asset and Liability Offset (Details) (USD $)	Apr. 03, 2015
In Thousands, unless otherwise specified
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Asset, Fair Value, Gross Asset	$148
Derivative Asset, Not Offset, Policy Election Deduction	0
Derivative Asset Fair Value Net Amount After Not Offset Policy Election Deduction	148
Derivative Asset, Collateral, Obligation to Return Cash, Offset	-18
Derivative Asset, Fair Value of Collateral	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	130
Derivative Liability, Fair Value, Gross Liability	18
Derivative Liability, Not Offset, Policy Election Deduction	0
Derivative Liability Fair Value Net Amount After Not Offset Policy Election	18
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	-18
Derivative Liability, Fair Value of Collateral	0
Derivative Liability, Fair Value, Amount Offset Against Collateral	$0

Fair_Value_Measurements_Financ

Fair Value Measurements - Financial Assets and Liabilities Measured at Fair Value Based on Three-Tier Fair Value Hierarchy (Detail) (USD $)	Apr. 03, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, Fair Value Disclosure, Nonrecurring	$0
Assets, Fair Value Disclosure, Nonrecurring	0
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	58,228,000	57,915,000
Total liabilities measured and recorded at fair value	18,000	7,000
Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	35,877,000	25,727,000
Total liabilities measured and recorded at fair value	0	0
Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	22,351,000	32,188,000
Total liabilities measured and recorded at fair value	18,000	7,000
Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	0	0
Total liabilities measured and recorded at fair value	0	0
Cash equivalents [Member] | Money market funds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	32,795,000	23,121,000
Cash equivalents [Member] | Level 1 [Member] | Money market funds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	32,795,000	23,121,000
Cash equivalents [Member] | Level 2 [Member] | Money market funds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	0	0
Cash equivalents [Member] | Level 3 [Member] | Money market funds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	0	0
Short-term investments [Member] | State, municipal and local government agencies bonds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	11,238,000	13,961,000
Short-term investments [Member] | Corporate bonds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	10,965,000	17,886,000
Short-term investments [Member] | Level 1 [Member] | State, municipal and local government agencies bonds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	0	0
Short-term investments [Member] | Level 1 [Member] | Corporate bonds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	0	0
Short-term investments [Member] | Level 2 [Member] | State, municipal and local government agencies bonds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	11,238,000	13,961,000
Short-term investments [Member] | Level 2 [Member] | Corporate bonds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	10,965,000	17,886,000
Short-term investments [Member] | Level 3 [Member] | State, municipal and local government agencies bonds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	0	0
Short-term investments [Member] | Level 3 [Member] | Corporate bonds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	0	0
Prepaids and other current assets [Member] | Foreign exchange forward contracts [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	148,000	341,000
Prepaids and other current assets [Member] | Level 1 [Member] | Foreign exchange forward contracts [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	0	0
Prepaids and other current assets [Member] | Level 2 [Member] | Foreign exchange forward contracts [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	148,000	341,000
Prepaids and other current assets [Member] | Level 3 [Member] | Foreign exchange forward contracts [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	0	0
Cost-method Investments [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	3,082,000	2,606,000
Cost-method Investments [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	3,082,000	2,606,000
Accrued Liabilities [Member] | Foreign exchange forward contracts [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities measured and recorded at fair value	18,000	7,000
Accrued Liabilities [Member] | Level 1 [Member] | Foreign exchange forward contracts [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities measured and recorded at fair value	0	0
Accrued Liabilities [Member] | Level 2 [Member] | Foreign exchange forward contracts [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities measured and recorded at fair value	18,000	7,000
Accrued Liabilities [Member] | Level 3 [Member] | Foreign exchange forward contracts [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities measured and recorded at fair value	$0	$0

Balance_Sheet_Components_Accou

Balance Sheet Components - Accounts Receivable, Net, Prepaid Expenses and Other Current Assets, Inventories, Property and Equipment, Net (Detail) (USD $)	Apr. 03, 2015		Dec. 31, 2014
In Thousands, unless otherwise specified
Accounts receivable, net:
Accounts receivable	$80,974		$81,201
Less: allowances for doubtful accounts, returns and discounts	-5,110		-7,057
Total	75,864		74,144
Prepaid expenses and other current assets:
Prepaid inventories to contract manufacturer(1)	14,200	[1]	0	[1]
Prepaid software license to Vislink(2)	1,090	[2]	1,233	[2]
Other Prepayments	9,953		9,713
Deferred cost of revenue	3,364		2,524
Income tax receivable	1,664		2,316
Other	255		1,753
Prepaid Expense and Other Assets, Current	30,526		17,539
Inventories:
Raw materials	1,844		1,422
Work-in-process	1,439		1,255
Finished goods	28,235		30,070
Total inventories, net	31,518		32,747
Property and equipment, net:
Furniture and fixtures	7,690		7,691
Machinery and equipment	116,895		116,031
Leasehold improvements	9,550		8,140
Property and equipment, gross	134,135		131,862
Less: accumulated depreciation and amortization	-106,995		-104,641
Property and equipment, net	$27,140		$27,221
[1]	In the first quarter of 2015, the Company made a $14.2 million advance payment for future inventory requirements to a supplier in order to secure more favorable pricing. The Company anticipates that this amount will begin to offset in the fourth quarter of 2015 through the first quarter of 2016 against the accounts payable owed to this supplier.
[2]	The prepaid inventories were related to prepayment for software licenses made to Vislink (see Note 4, “Investments in Other Equity Securities,” for additional information on Vislink).

Goodwill_and_Identified_Intang2

Goodwill and Identified Intangible Assets - Changes in Carrying Amount of Goodwill (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Apr. 03, 2015
Goodwill [Line Items]
Balance at beginning of period	$197,884
Foreign currency translation adjustment	-108
Balance at end of period	197,776
Video [Member]
Goodwill [Line Items]
Balance at beginning of period	136,975
Foreign currency translation adjustment	-75
Balance at end of period	136,900
Cable Edge [Member]
Goodwill [Line Items]
Balance at beginning of period	60,909
Foreign currency translation adjustment	-33
Balance at end of period	$60,876

Goodwill_and_Identified_Intang3

Goodwill and Identified Intangible Assets - Summary of Goodwill and Identified Intangible Assets (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Apr. 03, 2015	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	210,343	$210,343
Accumulated Amortization	-201,651	-199,744
Total future amortization expense	8,692	10,599
Developed core technology [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	136,145	136,145
Accumulated Amortization	-135,887	-135,426
Total future amortization expense	258	719
Developed core technology [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Useful Life	4 years
Developed core technology [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Useful Life	6 years
Customer relationships/contracts [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	67,098	67,098
Accumulated Amortization	-60,001	-58,784
Total future amortization expense	7,097	8,314
Customer relationships/contracts [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Useful Life	5 years
Customer relationships/contracts [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Useful Life	6 years
Maintenance agreements and related relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	7,100	7,100
Accumulated Amortization	-5,763	-5,534
Total future amortization expense	1,337	$1,566
Maintenance agreements and related relationships [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Useful Life	6 years
Maintenance agreements and related relationships [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Useful Life	7 years

Goodwill_and_Identified_Intang4

Goodwill and Identified Intangible Assets - Amortization Expense for Identifiable Purchased Intangible Assets (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Apr. 03, 2015	Mar. 28, 2014
Acquired Finite-Lived Intangible Assets [Line Items]
Total amortization expense	$1,907	$6,666
Included in cost of revenue [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Total amortization expense	461	4,716
Included in operating expenses [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Total amortization expense	$1,446	$1,950

Goodwill_and_Identified_Intang5

Goodwill and Identified Intangible Assets - Estimated Future Amortization Expense of Purchased Intangible Assets (Detail) (USD $)	Apr. 03, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Acquired Finite-Lived Intangible Assets [Line Items]
2015 (remaining 9 months)	$4,595
2016	4,097
Total future amortization expense	8,692	10,599
Product cost of revenue [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
2015 (remaining 9 months)	258
2016	0
Total future amortization expense	258
Operating Expenses [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
2015 (remaining 9 months)	4,337
2016	4,097
Total future amortization expense	$8,434

Restructuring_and_Related_Char2

Restructuring and Related Charges - Activities in Restructuring Accrual (Detail) (USD $)	3 Months Ended		12 Months Ended
	Apr. 03, 2015	Mar. 28, 2014	Dec. 31, 2014
Restructuring Cost and Reserve [Line Items]
Product cost of revenue	$0	$79,000
Restructuring and related charges	44,000	149,000
Restructuring and Related Cost, Incurred Cost	44,000	228,000
Harmonic Two Thousand And Fifteen Restructuring [Member]
Restructuring Reserve [Roll Forward]
Beginning Balance	322,000
Restructuring charges	56,000		2,200,000
Adjustments to restructuring provisions	-12,000
Cash payments	-321,000
Non-cash write-offs	2,000
Ending Balance	47,000		322,000
Harmonic Two Thousand And Fifteen Restructuring [Member] | Employee Severance And Benefit Arrangements [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	44,000
Restructuring Reserve [Roll Forward]
Beginning Balance	305,000
Restructuring charges	56,000		600,000
Adjustments to restructuring provisions	-5,000
Cash payments	-312,000
Non-cash write-offs	0
Ending Balance	44,000		305,000
Harmonic Two Thousand And Fifteen Restructuring [Member] | Other Restructuring [Member]
Restructuring Reserve [Roll Forward]
Beginning Balance	17,000
Restructuring charges	0		100,000
Adjustments to restructuring provisions	-7,000
Cash payments	-9,000
Non-cash write-offs	2,000
Ending Balance	$3,000		$17,000

Restructuring_and_Related_Char3

Restructuring and Related Charges - Additional Information (Detail) (USD $)	3 Months Ended		12 Months Ended
	Apr. 03, 2015	Mar. 28, 2014	Dec. 31, 2014	Dec. 31, 2013
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	$44,000	$228,000
Harmonic Two Thousand And Fifteen Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	56,000		2,200,000
Harmonic 2013 Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost		200,000	900,000	2,200,000
Fixed Asset Impairment [Member] | Harmonic Two Thousand And Fifteen Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges			1,100,000
Contract Termination [Member] | Harmonic Two Thousand And Fifteen Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges			300,000
Other Restructuring [Member] | Harmonic Two Thousand And Fifteen Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0		100,000
Employee Severance And Benefit Arrangements [Member] | Harmonic Two Thousand And Fifteen Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	56,000		600,000
Number of positions eliminated	2		19
Restructuring and Related Cost, Incurred Cost	$44,000
Employee Severance And Benefit Arrangements [Member] | Harmonic 2013 Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Number of positions eliminated		8

Credit_Facilities_Additional_I

Credit Facilities - Additional Information (Detail) (JPMorgan Chase [Member], USD $)	3 Months Ended
	Apr. 03, 2015	Dec. 22, 2014
Commercial Letters of Credit [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Commitment Fee Percentage	0.75%
Line of Credit Facility, Commitment Fee Amount	$100
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Percentage of Equity Interest Pledged as Collateral for Letter of Credit	66.67%
Line of Credit Facility, Current Borrowing Capacity		20,000,000
Line of Credit Facility, Remaining Borrowing Capacity	19,800,000
Borrowings under bank line of credit facility	0
Credit facility collateral	Obligations under the Credit Agreement are secured only by a pledge of 66 2/3% of the Company’s equity interests in its foreign subsidiary, Harmonic International AG. Additionally, to the extent that the Company in the future forms any direct or indirect, domestic, material subsidiaries, those subsidiaries will be required to provide a guaranty of the Company’s obligations under the Credit Agreement.
Line of Credit Facility, Threshold Consecutive Business Days	5 days
Debt Instrument, Fee Amount	50,000
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.25%
Line of Credit, Covenant, Consolidated Cash and Marketable Securities Minimum	35,000,000
Line of Credit Covenant, EBITDA, Minimum	20,000,000
Revolving Credit Facility [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Consolidated Cash Threshold	30,000,000
Standby letters of credit [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Current Borrowing Capacity		10,000,000
Line of Credit Facility, Remaining Borrowing Capacity	$200,000
Line of Credit Facility, Commitment Fee Percentage	1.75%
LIBOR [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
LIBOR rate duration	LIBOR
Adjusted LIBOR Rate, Variable Rate, Period End Month One	1 month
Adjusted LIBOR Rate, Variable Rate, Period End Month Two	2 months
Adjusted LIBOR Rate, Variable Rate, Period End Month Three	3 months
LIBOR [Member] | Revolving Credit Facility [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Line of Credit LIBOR margin	2.50%
Adjusted LIBOR Rate Applicable Margin Rate [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of Credit LIBOR margin	1.75%
Prime Rate [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
LIBOR rate duration	prime
Adjusted Prime Rate Applicable Margin Rate [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of Credit LIBOR margin	-1.30%

Employee_Benefit_Plans_Summary

Employee Benefit Plans - Summary of Company's Stock Option and Restricted Stock Unit Activity (Detail) (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Apr. 03, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Available for Grant, Beginning balance	7,480
Shares Available for Grant, Authorized
Shares Available for Grant, Granted	-3,037
Shares Available for Grant, Options exercised	0
Shares Available for Grant, Shares released	0
Shares Available for Grant, Forfeited or cancelled	283
Shares Available for Grant, Ending balance	4,726
Restricted Stock Units Outstanding [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Units, Beginning balance	2,241
Number of Shares, Authorized	0
Number of Units, Granted	1,325
Number of Units, exercised	0
Number of Units, Shares released	-925
Number of Units, Forfeited or cancelled	-73
Number of Units, Ending balance	2,568
Weighted Average Grant Date Fair Value, Beginning balance	6.4
Weighted Average Grant Date Fair Value, Authorized	0
Estimated weighted average fair value per share at purchase date	7.57
Weighted Average Grant Date Fair Value, Exercised	0
Weighted Average Grant Date Fair Value, Shares released	6.56
Weighted Average Grant Date Fair Value, Forfeited or cancelled	6.23
Weighted Average Grant Date Fair Value, Ending balance	7.01
Stock Options Outstanding [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Beginning balance	7,255
Number of Shares, Authorized	0
Number of Shares, Granted	1,049
Number of Shares, Options exercised	-617
Number of Shares, Forfeited or cancelled	-172
Number of Shares, Ending balance	7,515
Weighted Average Exercise Price, Beginning balance	6.65
Weighted Average Exercise Price, Authorized	0
Weighted Average Exercise Price, Granted	7.58
Weighted Average Exercise Price, Options exercised	5.49
Weighted Average Exercise Price, Forfeited or cancelled	6.86
Weighted Average Exercise Price, Ending balance	6.87

Employee_Benefit_Plans_Summary1

Employee Benefit Plans - Summary of Stock Options Outstanding (Detail) (Stock Options Outstanding [Member], USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Apr. 03, 2015
Stock Options Outstanding [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Vested and expected to vest	7,126
Weighted Average Exercise Price, Vested and expected to vest	$6.87
Weighted Average Remaining Contractual Term (Years), Vested and expected to vest	3 years 8 months 12 days
Aggregate Intrinsic Value, Vested and expected to vest	$6,331
Number of Shares, Exercisable	4,694
Weighted Average Exercise Price, Exercisable	$6.94
Weighted Average Remaining Contractual Term (Years), Exercisable	2 years 6 months
Aggregate Intrinsic Value, Exercisable	$4,571

Employee_Benefit_Plans_Summary2

Employee Benefit Plans - Summary of Restricted Stock Units Outstanding (Detail) (Restricted Stock Units Outstanding [Member], USD $)	3 Months Ended
In Thousands, unless otherwise specified	Apr. 03, 2015
Restricted Stock Units Outstanding [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares Underlying Restricted Stock Units	2,359
Weighted Average Remaining Vesting Period (Years)	0 years 9 months 28 days
Aggregate Fair Value	$17,407

Employee_Benefit_Plans_Additio

Employee Benefit Plans - Additional Information (Detail) (USD $)	3 Months Ended
	Apr. 03, 2015	Mar. 28, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Intrinsic value of options exercised	$1,300,000	$100,000
Increase in authorized shares for ESPP
Discretionary contributions of plan	25.00%
Percent of employees' gross pay eligible for matching	4.00%
Maximum contribution amount per participant	1,000
Contributions in period	$161,000	$173,000
Defined contribution plan description	The Company has a retirement/savings plan which qualifies as a thrift plan under Section 401(k) of the Internal Revenue Code. This plan allows participants to contribute up to the applicable Internal Revenue Code limitations under the plan. The Company has made discretionary contributions to the plan of 25% of the first 4% contributed by eligible participants, up to a maximum contribution per participant of $1,000 per year.
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of fair market value of Common Stock to purchase shares	85.00%
Minimum [Member] | Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Stock Purchase Plan Payroll Deductions	1.00%
Maximum [Member] | Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Stock Purchase Plan Payroll Deductions	10.00%

StockBased_Compensation_Summar

Stock-Based Compensation - Summary of Stock-Based Compensation Expense (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Apr. 03, 2015	Mar. 28, 2014
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	$4,134	$3,807
Product cost of revenue [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	528	516
Research and development expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	1,148	1,101
Selling, general and administrative expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	2,458	2,190
Operating Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	$3,606	$3,291

StockBased_Compensation_Valuat

Stock-Based Compensation - Valuation Assumptions for Stock Options (Detail) (USD $)	3 Months Ended		6 Months Ended
	Apr. 03, 2015	Mar. 28, 2014	Jun. 30, 2014	Jun. 30, 2015
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividends	0.00%
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (years)	4 years 8 months 13 days	4 years 8 months 13 days
Volatility	38.00%	40.00%
Risk-free interest rate	1.60%	1.70%
Expected dividends	0.00%	0.00%
Purchase Period June 30, 2014 [Member] | Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (years)			0 years 6 months 1 day
Volatility			29.00%
Risk-free interest rate			0.10%
Expected dividends			0.00%
Estimated weighted average fair value per share at purchase date			$1.71
Purchase Period June 30, 2015 [Member] | Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (years)	0 years 5 months 27 days
Volatility	35.00%
Risk-free interest rate	0.10%
Expected dividends	0.00%
Scenario, Forecast [Member] | Purchase Period June 30, 2015 [Member] | Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Estimated weighted average fair value per share at purchase date				$1.74

StockBased_Compensation_Additi

Stock-Based Compensation - Additional Information (Detail) (USD $)	3 Months Ended
	Apr. 03, 2015	Mar. 28, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average fair value per share of options granted	$2.63	$2.35
Fair value of options vested	$1,300,000	$1,300,000
Total realized tax benefit	120,000	185,000
Increase in authorized shares for ESPP
Total unamortized stock-based compensation cost related to unvested stock options and restricted stock units	20,100,000
Remaining weighted-average amortization period	2 years 1 month 21 days
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0.00%	0.00%
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0.00%
Discount percentage on purchase of stock	15.00%
Fair Value of stock purchase rights percentage of call option	85.00%
Value of stock purchase rights percentage of put option	15.00%
Restricted Stock Units Outstanding [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of restricted stocks fair value	$6,100,000	$5,400,000

StockBased_Compensation_Employ

Stock-Based Compensation - Employee Stock Purchase Plan (Detail) (Employee Stock Purchase Plan [Member], USD $)	3 Months Ended	6 Months Ended
	Apr. 03, 2015	Jun. 30, 2014	Jun. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividends	0.00%
Purchase Period June 30, 2014 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (years)		0 years 6 months 1 day
Volatility		29.00%
Risk-free interest rate		0.10%
Expected dividends		0.00%
Estimated weighted average fair value per share at purchase date		$1.71
Purchase Period June 30, 2015 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (years)	0 years 5 months 27 days
Volatility	35.00%
Risk-free interest rate	0.10%
Expected dividends	0.00%
Scenario, Forecast [Member] | Purchase Period June 30, 2015 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Estimated weighted average fair value per share at purchase date			$1.74

Income_Taxes_Details

Income Taxes (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Apr. 03, 2015	Mar. 28, 2014
Income Tax Disclosure [Abstract]
Loss before income taxes	($2,943)	($7,133)
Benefit from income taxes	($286)	($1,723)
Effective income tax rate	9.70%	24.20%

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Apr. 03, 2015	Mar. 28, 2014
Income Tax Contingency [Line Items]
Effective income tax rate	9.70%	24.20%
Federal statutory income tax rate	35.00%	35.00%
Unrecognized tax benefits that would impact the provision for income taxes	$16.30
Interest and possible penalties related to uncertain tax positions	0.6
Potential decrease over the next twelve months for uncertain tax positions due to expiration of applicable statute of limitations	$1
SWITZERLAND
Income Tax Contingency [Line Items]
Income Tax Holiday, Description	The Company's operations in Switzerland are subject to a reduced tax rate under the Switzerland tax holiday which requires various thresholds of investment and employment in Switzerland. The Company has met these various thresholds and the Switzerland tax holiday is effective through the end of 2018.
Pro Forma [Member]
Income Tax Contingency [Line Items]
Federal statutory income tax rate	65.00%

Income_Loss_Per_Share_Numerato

Income (Loss) Per Share - Numerators and Denominators of Basic and Diluted Net Income (Loss) Per Share Computations (Detail) (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Apr. 03, 2015	Mar. 28, 2014
Numerator:
Net loss	($2,657)	($5,410)
Denominator:
Basic and diluted	88,655	97,921
Net loss per share:
Basic and diluted	($0.03)	($0.06)

Income_Loss_Per_Share_Antidilu

Income (Loss) Per Share - Anti-dilutive Securities (Detail)	3 Months Ended
In Thousands, unless otherwise specified	Apr. 03, 2015	Mar. 28, 2014
Earnings Per Share [Abstract]
Potentially dilutive equity awards outstanding	9,641	11,072

Segment_Information_Details

Segment Information (Details) (USD $)	3 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Apr. 03, 2015	Mar. 28, 2014	Dec. 31, 2014	Dec. 31, 2013
			segment	segment
Segment Reporting Information [Line Items]
Revenue, Net	$104,016	$108,032
Number of Reportable Segments			2	1
Income (loss) from operations	13	-7,222
Operating Expenses	-55,015	-59,534
Stock-based compensation	-4,134	-3,807
Amortization of Intangible Assets	-1,907	-6,666
Nonoperating Income (Expense)	-2,956	89
Loss before income taxes	-2,943	-7,133
Video [Member]
Segment Reporting Information [Line Items]
Revenue, Net	69,282	81,152
Cable Edge [Member]
Segment Reporting Information [Line Items]
Revenue, Net	34,734	26,880
Operating Segments [Member]
Segment Reporting Information [Line Items]
Income (loss) from operations	6,098	3,479
Operating Segments [Member] | Video [Member]
Segment Reporting Information [Line Items]
Income (loss) from operations	-90	2,435
Operating Segments [Member] | Cable Edge [Member]
Segment Reporting Information [Line Items]
Income (loss) from operations	6,188	1,044
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Operating Expenses	($44)	($228)

Commitments_and_Contingencies_1

Commitments and Contingencies - Additional Information (Detail) (USD $)	Apr. 03, 2015	Jun. 29, 2012	Oct. 31, 2011
		Patents	Patents
Contingencies And Commitments [Line Items]
Future sublease income	$131,000
Non-cancelable purchase commitments	22,600,000
Maximum amount of potential future payments under the company's financial guarantees	400,000
Infringements of number of patents held		1	2
Israel [Member]
Contingencies And Commitments [Line Items]
Guarantees related to rent obligations	400,000
Indemnification [Member]
Contingencies And Commitments [Line Items]
Accrual for indemnification provisions	$0

Commitments_and_Contingencies_2

Commitments and Contingencies - Future Minimum Lease Payments Under Non-cancelable Operating Leases (Detail) (USD $)	Apr. 03, 2015
In Thousands, unless otherwise specified
Commitments and Contingencies Disclosure [Abstract]
2015 (remaining 9 months)	$7,591
2016	8,788
2017	8,067
2018	7,933
2019	7,885
Thereafter	6,133
Total	$46,397

Commitments_and_Contingencies_3

Commitments and Contingencies - Summary of Warranty Accrual Included in Accrued Liabilities (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Apr. 03, 2015	Mar. 28, 2014
Commitments and Contingencies Disclosure [Abstract]
Balance at beginning of period	$4,242	$3,606
Accrual for current period warranties	1,595	1,749
Warranty costs incurred	-1,746	-1,696
Balance at end of period	$4,091	$3,659

Stockholders_Equity_Components

Stockholders' Equity - Components of Accumulated Other Comprehensive Loss (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Apr. 03, 2015	Mar. 28, 2014	Dec. 31, 2014
Equity [Abstract]
Foreign currency translation adjustments	($2,507)		($1,523)
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax	78		311
Unrealized gain on investments	-287		-768
Accumulated Other Comprehensive Loss	-2,716		-1,980
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax	-984	40
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax	-184	0
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Tax	485	7
Other Comprehensive Income (Loss), before Reclassifications, before Tax	-683
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, before Tax	0
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax	-49	0
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI for Write-down of Securities, before Tax	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	-49
Other Comprehensive Income (Loss), Foreign Currency Translation Gain (Loss) Arising During Period, Tax	0
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax	0
Other Comprehensive Income (Loss), Available-for-sale Securities, Tax	-4
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	($4)

Stockholders_Equity_Stockholde

Stockholders' Equity Stockholders' Equity - Reclassification from AOCI to Statement of Operations (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Apr. 03, 2015	Mar. 28, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion	$49	$0
Product cost of revenue [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion	7	0
Operating Expense [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion	$42	$0

Stockholders_Equity_Additional

Stockholders' Equity - Additional Information (Detail) (USD $)	0 Months Ended	12 Months Ended	35 Months Ended
In Millions, except Per Share data, unless otherwise specified	14-May-14	Dec. 31, 2013	Apr. 03, 2015	14-May-14	Apr. 24, 2012
Stockholders' Equity Note [Abstract]
Authorized stock repurchase value		$220		$300	$25
Increase in stock repurchase program	80	195
Stock Repurchased and Retired During Period, Shares			37.9
Weighted average purchase price per share			$6.23
Stock Repurchased and Retired During Period, Value			237.5
Stock Repurchased and Retired During Period, Expenses			1
Remaining authorized repurchase amount			$63.50