Riverbed Technology 10-K 13 Feb 15 2014 FY Annual report Financial data

Document_And_Entity_Informatio

Document And Entity Information (USD $)	12 Months Ended
	Dec. 31, 2014	Feb. 06, 2015	Jun. 30, 2014
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	FALSE
Document Period End Date	31-Dec-14
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Trading Symbol	rvbd
Entity Registrant Name	Riverbed Technology, Inc.
Entity Central Index Key	1357326
Current Fiscal Year End Date	-19
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		157,781,493
Entity Public Float			$1,812,063,075
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Well-known Seasoned Issuer	Yes

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets:
Cash and cash equivalents	$296,384	$208,022
Short-term investments	212,789	251,339
Trade receivables, net of allowances of $1,544 and $1,996 as of December 31, 2014 and 2013, respectively	104,028	93,836
Inventory	14,786	25,025
Deferred tax assets	31,802	7,222
Assets Held-for-sale, Current	30,965	0
Prepaid expenses and other current assets	54,227	49,016
Total current assets	744,981	634,460
Long-term investments	104,733	72,675
Fixed assets, net	70,800	57,810
Goodwill	669,716	704,305
Intangibles, net	304,544	404,467
Other assets	31,714	23,881
Total assets	1,926,488	1,897,598
Current liabilities:
Accounts payable	47,011	45,518
Accrued compensation and benefits	48,740	51,988
Other accrued liabilities	62,135	36,520
Current maturities of long-term borrowings	15,000	15,000
Liabilities of Assets Held-for-sale	9,586	0
Deferred revenue	219,600	217,131
Total current liabilities	402,072	366,157
Deferred revenue, non-current	94,552	95,344
Borrowings, non-current, net of current maturities	495,000	510,000
Deferred tax liability, non-current	46,933	48,548
Other long-term liabilities	47,335	48,910
Total long-term liabilities	683,820	702,802
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.0001 par value — 30,000 shares authorized, no shares outstanding	0	0
Common stock and additional paid-in-capital; $0.0001 par value — 600,000 shares authorized; 157,670 and 159,845 shares issued and outstanding as of December 31, 2014 and 2013, respectively	649,697	702,928
Retained earnings	196,563	125,295
Accumulated other comprehensive income (loss)	-5,664	416
Total stockholders’ equity	840,596	828,639
Total liabilities and stockholders’ equity	$1,926,488	$1,897,598

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified
Statement of Financial Position [Abstract]
Trade receivables, allowances	$1,544	$1,996
Preferred stock, par value	$0.00	$0.00
Preferred stock, shares authorized	30,000	30,000
Preferred stock, shares outstanding	0	0
Common stock, par value	$0.00	$0.00
Common stock, shares authorized	600,000	600,000
Common stock, shares issued	157,670	159,845
Common stock, shares outstanding	157,670	159,845

Consolidated_Statements_Of_Ope

Consolidated Statements Of Operations (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenue:
Product	$605,414	$614,498	$548,141
Support and services	483,794	426,535	288,719
Total revenue	1,089,208	1,041,033	836,860
Cost of revenue:
Cost of product	150,032	164,774	124,406
Cost of support and services	131,878	117,157	80,412
Total cost of revenue	281,910	281,931	204,818
Gross profit	807,298	759,102	632,042
Operating expenses:
Sales and marketing	454,945	469,200	328,657
Research and development	205,591	189,654	146,108
General and administrative	76,535	73,339	60,594
Other Cost and Expense, Operating	21,927	18,322	726
Total operating expenses	758,998	750,515	536,085
Operating income	48,300	8,587	95,957
Other income (expense), net
Interest income	1,264	838	1,645
Interest and other expense, net	-12,145	-35,990	-3,569
Gain on sale of assets	57,451	0	0
Total other income (expense), net	46,570	-35,152	-1,924
Income (loss) before provision for (benefit from) income taxes	94,870	-26,565	94,033
Provision for (benefit from) income taxes	23,602	-14,147	39,436
Net income (loss)	$71,268	($12,418)	$54,597
Net income (loss) per common share:
Basic	$0.45	($0.08)	$0.35
Diluted	$0.44	($0.08)	$0.33
Shares used in computing net income (loss) per common share:
Basic	158,680	162,707	156,205
Diluted	163,192	162,707	164,570

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net income (loss)	$71,268	($12,418)	$54,597
Other comprehensive income (loss):
Unrealized gain (loss) on investments, net of tax	-44	-38	28
Foreign currency translation adjustment	-2,144	1,247	2,670
Derivative instruments gain (loss), net of tax	-3,892	475	7
Other comprehensive income (loss)	-6,080	1,684	2,705
Comprehensive income (loss)	$65,188	($10,734)	$57,302

Consolidated_Statements_Of_Sto

Consolidated Statements Of Stockholders' Equity (USD $)	Total	Common Stock And Additional Paid-In-Capital [Member]	Retained Earnings (Accumulated Deficit) [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
In Thousands, except Share data, unless otherwise specified
Balance at Dec. 31, 2011	$711,064	$631,921	$83,116	($3,973)
Balance, shares at Dec. 31, 2011		157,454,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Shares, Acquisitions		6,503,000
Stock Issued During Period, Value, Acquisitions	123,231	123,231
Repurchase of common stock	-127,144	-127,144
Repurchase of common stock, shares		-7,377,000
Common stock issued under stock plans, net of shares withheld for employee taxes	20,297	20,297
Common stock issued under stock plans, net of shares withheld for employee taxes, shares		6,756,000
Tax benefit from employee stock plans	20,178	20,178
Stock-based compensation	89,294	89,294
Net income (loss)	54,597		54,597
Other comprehensive income	2,705			2,705
Balance at Dec. 31, 2012	894,222	757,777	137,713	-1,268
Balance, shares at Dec. 31, 2012		163,336,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of common stock	-200,081	-200,081
Repurchase of common stock, shares		-12,418,000
Common stock issued under stock plans, net of shares withheld for employee taxes	57,699	57,699
Common stock issued under stock plans, net of shares withheld for employee taxes, shares		8,927,000
Tax benefit from employee stock plans	-3,024	-3,024
Stock-based compensation	90,557	90,557
Net income (loss)	-12,418		-12,418
Other comprehensive income	1,684			1,684
Balance at Dec. 31, 2013	828,639	702,928	125,295	416
Balance, shares at Dec. 31, 2013	159,845	159,845,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of common stock	-195,571	-195,571
Repurchase of common stock, shares		-10,166,000
Common stock issued under stock plans, net of shares withheld for employee taxes	49,568	49,568
Common stock issued under stock plans, net of shares withheld for employee taxes, shares		7,991,000
Tax benefit from employee stock plans	2,265	2,265
Stock-based compensation	90,507	90,507
Net income (loss)	71,268		71,268
Other comprehensive income	-6,080			-6,080
Balance at Dec. 31, 2014	$840,596	$649,697	$196,563	($5,664)
Balance, shares at Dec. 31, 2014	157,670	157,670,000

Consolidated_Statements_Of_Cas

Consolidated Statements Of Cash Flows (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating Activities:
Net income (loss)	$71,268	($12,418)	$54,597
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	113,757	126,166	40,010
Stock-based compensation	90,507	90,557	89,294
Disposal Group, Not Discontinued Operation, Gain/Loss on Disposal	-57,451	0	0
Write off of deferred debt issuance costs	0	12,269	0
Deferred taxes	-25,866	-55,182	5,557
Excess tax benefit from employee stock plans	-7,367	-8,636	-23,883
Other Noncash Income (Expense)	910	1,971	0
Changes in operating assets and liabilities:
Trade receivables	-10,132	19,354	-13,386
Inventory	8,908	-850	-6,238
Prepaid expenses and other assets	294	5,892	7,776
Accounts payable	7,834	-10,632	4,567
Accrued and other liabilities	20,052	10,015	-14,722
Acquisition-related contingent consideration	0	0	-15,882
Income taxes payable	2,265	-3,022	20,176
Deferred revenues	12,703	41,862	91,397
Net cash provided by operating activities	227,682	217,346	239,263
Investing Activities:
Capital expenditures	-49,307	-25,625	-21,956
Proceeds from Sale of Productive Assets	65,788	0	0
Purchase of available for sale securities	-372,719	-401,145	-444,472
Proceeds from maturities of available for sale securities	304,736	299,678	344,353
Proceeds from sales of available for sale securities	72,737	24,045	257,961
Acquisitions, net of cash and cash equivalents acquired	-679	-1,000	-790,269
Net cash provided by (used in) investing activities	20,556	-104,047	-654,383
Financing Activities:
Proceeds from issuance of common stock under employee stock plans, net of repurchases	71,958	72,764	47,606
Taxes paid related to net share settlement of equity awards	-22,390	-15,065	-27,309
Payments for repurchases of common stock	-195,571	-200,081	-127,144
Payments of borrowings	-15,000	-575,000	0
Proceeds from borrowings of debt and revolving credit line, net of issuance costs	0	521,234	560,371
Excess tax benefit from employee stock plans	7,367	8,636	23,883
Net cash (used in) provided by financing activities	-153,636	-187,512	477,407
Effect of exchange rate changes on cash and cash equivalents	-6,240	1,726	2,746
Net increase (decrease) in cash and cash equivalents	88,362	-72,487	65,033
Cash and cash equivalents at beginning of period	208,022	280,509	215,476
Cash and cash equivalents at end of period	296,384	208,022	280,509
Cash Flow, Noncash Financing Activities
Fair market value of common stock issued and options assumed from acquisitions	0	0	123,231
Supplemental schedule of cash flow data:
Cash paid for income taxes	51,004	3,631	8,827
Cash paid for interest	$10,368	$22,205	$247

Organization_And_Significant_A

Organization And Significant Accounting Policies

12 Months Ended

Dec. 31, 2014

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Organization And Significant Accounting Policies

ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES

Organization

Riverbed Technology, Inc. was founded on May 23, 2002 and is a leader in application performance infrastructure. Riverbed gives enterprises the visibility to deliver, control, and optimize IT resources across the hybrid enterprise through the Riverbed Application Performance Platform, a set of integrated solutions that give companies the flexibility to host applications and data in the locations that best serve the business while ensuring the flawless delivery of those applications to better leverage global resources, radically reduce the cost of running their business, and maximize employee productivity. Riverbed’s solutions dramatically improve application performance, reduce IT costs, and substantially increase business agility.

Pending Merger

On December 14, 2014, we entered into an agreement and plan of merger (Merger Agreement) with Project Homestake Holdings, LLC (Newco) and Project Homestake Merger Sub Corp., a wholly owned subsidiary of Newco (Merger Sub), providing for the acquisition of Riverbed by the private equity investment firm Thoma Bravo for $21.00 in cash per outstanding common share (the Merger). Newco and Merger Sub were formed by an affiliate of private equity investment firm Thoma Bravo. Capitalized terms not otherwise defined have the meaning set forth in the Merger Agreement.

At the Effective Time of the Merger, each share of common stock of the Company (the Company Common Stock) issued and outstanding as of immediately prior to the Effective Time (other than Owned Shares or Dissenting Shares) will be cancelled and extinguished and automatically converted into the right to receive cash in an amount equal to $21.00, without interest thereon (the Per Share Price). Company Options and Restricted Stock Units generally will be cancelled and converted into the right to receive the Per Share Price, less, in the case of Company Options the exercise price per share.

Newco and Merger Sub have secured committed financing, consisting of a combination of equity to be provided by investment funds affiliated with Thoma Bravo, Teachers’ Private Capital, the private investor department of Ontario Teachers’ Pension Plan (OTTP), and certain other institutional equity co-investors, and debt financing from Credit Suisse Securities (USA) LLC, Citigroup Global Markets Inc. and certain of its affiliates, and Barclays Bank PLC, the aggregate proceeds of which will be sufficient for Newco and Merger Sub to pay the aggregate merger consideration and all related fees and expenses. Newco and Merger Sub have committed to use their reasonable best efforts to obtain the debt financing on the terms and conditions described in the debt commitment letter entered into as of December 12, 2014. The transaction is not subject to a financing condition.

Consummation of the Merger is subject to customary closing conditions, including, without limitation, the absence of certain legal impediments, the expiration or termination of the required waiting periods under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended, antitrust regulatory approval in Germany, review and clearance by the Committee on Foreign Investment in the United States, and approval by the Company’s stockholders.

The Company has made customary representations and warranties in the Merger Agreement and has agreed to customary covenants regarding the operation of the business of the Company and its Subsidiaries prior to the Effective Time. The Company is also subject to customary restrictions on its ability to solicit alternative acquisition proposals from third parties and to provide non-public information to, and participate in discussions and engage in negotiations with, third parties regarding alternative acquisition proposals, with customary exceptions for Superior Proposals.

The Merger Agreement contains certain termination rights for the Company and Newco. Upon termination of the Merger Agreement under specified circumstances, the Company will be required to pay Newco a termination fee of $126.0 million. If the Merger Agreement is terminated in connection with the Company accepting a Superior Proposal or due to the Board of Directors’ change or withdrawal of its recommendation of the Merger, then the termination fee will become payable by the Company to Newco. This termination fee will also be payable if the Merger Agreement is terminated because the Company’s stockholders did not vote to adopt the Merger Agreement and prior to such termination, a proposal to acquire at least 50% of the Company’s stock or assets is publicly announced and the Company enters into an agreement for, or completes, a transaction contemplated by such proposal within one year of termination. In addition, the Company will be required to reimburse Newco for up to $4.0 million of its expenses associated with the transaction if the Merger Agreement is terminated because the Company’s stockholders do not vote to adopt the Merger Agreement or if the Company breaches its representations, warranties or covenants in a manner that would cause the related closing conditions to not be met.

Significant Accounting Policies

Basis of Financial Statements

The consolidated financial statements include our accounts and the accounts of our wholly owned subsidiaries. Intercompany transactions and balances have been eliminated.

Use of Estimates

Our consolidated financial statements are prepared in United States (U.S.) generally accepted accounting principles (GAAP). These accounting principles require us to make certain estimates and judgments that can affect the reported amounts of assets and liabilities as of the date of the consolidated financial statements, as well as the reported amounts of revenue and expenses during the periods presented. Significant estimates and assumptions made by management include the determination of the fair value of stock awards issued, inventory valuation, the accounting for income taxes, including the determination of the valuation allowance related to our deferred tax asset balances, liabilities for uncertain tax positions, goodwill and other intangible assets, and the accounting for business combinations. We believe that the estimates and judgments upon which we rely are reasonable based upon information available to us at the time that these estimates and judgments were made. To the extent there are material differences between these estimates and actual results, our consolidated financial statements will be affected.

Cash and Cash Equivalents

We consider all highly liquid investments purchased with original maturities at the date of purchase of three months or less to be cash equivalents. Cash and cash equivalents are stated at cost, which approximates fair value.

Investments

We determine the appropriate classification of short and long-term investments at the time of purchase and re-evaluate such determination at each balance sheet date. The fair value of our investments is determined as the exit price in the principal market in which we would transact. Securities, which are classified as available for sale at December 31, 2014, 2013 and 2012, are carried at fair value, with the unrealized gains and losses, net of tax, reported as a separate component of stockholders’ equity. Unrealized gains and losses to date have not been material. Realized gains and losses and declines in value judged by us to be other-than-temporary on securities available for sale are included as a component of Interest expense and other, net. The cost of securities sold is based on the specific-identification method. Interest on securities classified as available for sale is included as a component of Interest expense and other, net.

Inventory Valuation

Inventory consists of hardware and related component parts and is stated at the lower of cost (on a first-in, first-out basis) or market. A portion of our inventory relates to evaluation units located at customer locations, as some of our customers test our equipment prior to purchasing. Inventory that is obsolete or in excess of our forecasted demand is written down to its estimated realizable value based on historical usage, expected demand, and with respect to evaluation units, the historical conversion rate, the age of the units, and the estimated loss of utility. Inherent in our estimates of market value in determining inventory valuation are estimates related to economic trends, future demand for our products, the timing of new product introductions and technological obsolescence of our products. Inventory write-downs, including estimated loss of utility on evaluation units, are recognized as cost of product and amounted to approximately $8.0 million, $11.2 million and $6.7 million for the years ended December 31, 2014, 2013 and 2012, respectively.

Service Inventory

We hold service inventory that is used to repair or replace defective hardware reported by our customers who purchase support services. We classify service inventory as Prepaid expenses and other current assets. At December 31, 2014 and 2013 our service inventory balance was $21.1 million and $20.8 million, respectively.

Internal-Use Software Development Costs

We capitalize qualifying costs for computer software developed for or obtained for internal-use, which are incurred during the application development stage, and amortize them over the software’s estimated useful life, which is generally two to five years.

We capitalized $9.9 million, $7.7 million and $6.9 million in internal use software during the years ended December 31, 2014, 2013 and 2012, respectively. Amortization expense related to these assets totaled $8.2 million, $6.7 million and $4.8 million during the years ended December 31, 2014, 2013 and 2012, respectively. Software development costs required to be capitalized for software sold, leased, or otherwise marketed have not been material to date.

Impairment of Long-Lived Assets

We review long-lived assets and identifiable intangible assets, excluding goodwill, for impairment whenever events or changes in circumstances indicate that the carrying amount of these assets may not be recoverable. We assess these assets for impairment based on estimated undiscounted future cash flows from these assets. If the carrying value of the assets exceeds the estimated future undiscounted cash flows, a loss is recorded for the excess of the asset’s carrying value over the fair value. To date we have not recognized any impairment loss for long-lived assets.

Goodwill, Intangible Assets and Impairment Assessments

Goodwill represents the excess of the purchase price of an acquired business over the fair value of the underlying net tangible and intangible assets. Goodwill is tested for impairment at least annually (more frequently if certain indicators are present). In the event that we determine that the fair value of a reporting unit is less than the reporting unit’s carrying value, we will incur an impairment charge for the amount of the difference during the quarter in which the determination is made.

Intangible assets that are not considered to have an indefinite life are amortized over their useful lives. On a periodic basis, we evaluate the estimated remaining useful life of purchased intangible assets and whether events or changes in circumstances warrant a revision to the remaining period of amortization. The carrying amounts of these assets are periodically reviewed for impairment whenever events or changes in circumstances indicate that the carrying value of these assets may not be recoverable. Recoverability of these assets is measured by comparison of the carrying amount of each asset to the future undiscounted cash flows the asset is expected to generate.

In the event that we determine that the fair value of an intangible asset is less than the carrying value, we will incur an impairment charge for the amount of the difference during the quarter in which the determination is made. We did not recognize any material goodwill or intangible asset impairment charges in the years ended December 31, 2014, 2013 or 2012.

Revenue Recognition

We recognize revenue when all of the following have occurred: (1) we have entered into a legally binding arrangement with a customer; (2) delivery has occurred; (3) customer payment is deemed fixed or determinable and free of contingencies and significant uncertainties; and (4) collection is reasonably assured.

The majority of our product revenue includes hardware appliances containing software components that function together to provide the essential functionality of the product. Therefore, our hardware appliances are considered non-software deliverables. Most non-software products and services qualify as separate units of accounting because they have value to the customer on a standalone basis and our revenue arrangements generally do not include a general right of return relative to delivered products. We account for non-software arrangements with multiple deliverables, which generally include support services sold with each of our hardware appliances, using the relative selling price method under the revenue recognition guidance for multiple deliverable arrangements.

Our product revenue also includes revenue from the sale of stand-alone software products. Stand-alone software may operate on our hardware appliance, but is not considered essential to the functionality of the hardware. Stand-alone software products generally include a perpetual license to our software. Stand-alone software sales are subject to the industry specific software revenue recognition guidance.

Certain arrangements with multiple deliverables may have stand-alone software deliverables that are subject to the software revenue recognition guidance along with non-software deliverables. The revenue for these multiple deliverable arrangements is allocated to the stand-alone software deliverables as a group and the non-software deliverables based on the relative selling prices of all of the deliverables in the arrangement.

The amount of product and services revenue recognized for arrangements with multiple deliverables is impacted by their relative selling prices. We apply the selling price hierarchy using vendor specific objective evidence (VSOE) when available, third-party evidence of selling price (TPE) if VSOE does not exist, and estimated selling price (ESP) if neither VSOE nor TPE is available.

VSOE of fair value for elements of an arrangement is based upon the normal pricing and discounting practices for a deliverable when sold separately, and VSOE for support services is measured by the renewal rate offered to the customer. In determining VSOE, we require that a substantial majority of the selling prices fall within a reasonably narrow pricing range, generally evidenced by a substantial majority of such historical stand-alone transactions falling within a reasonably narrow range of the median rates. In addition, we consider major service groups, geographies, customer classifications, and other variables in determining VSOE.

We are typically not able to determine TPE for our products or services. TPE is determined based on competitor prices for similar deliverables when sold separately. Generally, our go-to-market strategy differs from that of our peers and our offerings contain a significant level of differentiation such that the comparable pricing of products with similar functionality cannot be obtained. Furthermore, we are unable to reliably determine what similar competitor products’ selling prices are on a stand-alone basis.

When we are unable to establish the estimated stand-alone value of our non-software deliverables using VSOE or TPE, we use ESP in our allocation of arrangement consideration. The objective of ESP is to determine the price at which we would transact a sale if the product or service were sold on a stand-alone basis. We determine ESP for a product or service by considering multiple factors including, but not limited to, cost of products, gross margin objectives, pricing practices, geographies, customer classes and distribution channels.

For stand-alone software sales, we recognize revenue based on software revenue recognition guidance. Under the software revenue recognition guidance, we use the residual method to recognize revenue when an agreement includes one or more elements to be delivered at a future date and VSOE of the fair value of all undelivered elements exists. In the majority of our contracts, the only element that remains undelivered at the time of delivery of the product is support services. Under the residual method, the fair value of the undelivered stand-alone software, which is typically support services, is deferred and the remaining portion of the contract fee is recognized as product revenue. If evidence of the fair value of one or more undelivered stand-alone software elements does not exist, all revenue is generally deferred and recognized when delivery of those elements occurs or when fair value can be established. When the undelivered stand-alone element for which we do not have VSOE of fair value is support, revenue for the entire arrangement is bundled and recognized ratably over the support period.

For our non-software deliverables, we allocate the arrangement consideration based on the relative selling price of the deliverables. For our hardware appliances we use the ESP of the deliverable. For our support and services, we generally use VSOE as our relative selling price. When we are unable to establish VSOE for our support and services, we use ESP in our allocation of arrangement consideration. We regularly review VSOE and ESP. As our go-to-market strategies evolve, we may modify our pricing practices in the future, which could result in changes in selling prices, including both VSOE and ESP.

For sales to direct end-users and channel partners, including value-added resellers, value-added distributors, service providers, and systems integrators, we recognize product revenue upon delivery, assuming all other revenue recognition criteria are met. For our hardware appliances, delivery occurs upon transfer of title and risk of loss, which is generally upon shipment. It is our practice to identify an end-user prior to shipment to a channel partner. For end-users and channel partners, we generally have no significant obligations for future performance such as rights of return or pricing credits. Shipping charges billed to customers are included in product revenue and the related shipping costs are included in cost of product revenue.

Support and services consist of support services, professional services, and training. Support services include repair and replacement of defective hardware appliances, software updates and access to technical support personnel. Software updates provide customers with rights to unspecified software product upgrades and to maintenance releases and patches released during the term of the support period on a when-and-if-available basis. Open-enrollment training services which are delivered on a when-and-if-available basis may be bundled with support services. Revenue for support services is recognized on a straight-line basis over the service contract term, which is typically one to three years. Professional services are recognized upon delivery or completion of performance. Professional service arrangements are typically short term in nature and are largely completed within 90 days from the start of service. Training services are recognized upon delivery of the training.

Our fees are typically considered to be fixed or determinable at the inception of an arrangement, generally based on specific products and quantities to be delivered. Substantially all of our contracts do not include rights of return or acceptance provisions. To the extent that our agreements contain such terms, we recognize revenue once the acceptance provisions or right of return lapses. Payment terms to customers generally range from net 30 to 90 days. In the event payment terms are provided that significantly differ from our standard business practices, the fees may be deemed to not be fixed or determinable and revenue is recognized when the payments become due, provided the remaining criteria for revenue recognition have been met.

We assess the ability to collect from our customers based on a number of factors, including credit worthiness of the customer and past transaction history of the customer. If the customer is not deemed credit worthy, we defer revenue from the arrangement until payment is received and all other revenue recognition criteria have been met.

Stock-Based Compensation

Stock-based awards granted include restricted stock units (RSUs), stock purchased under our Employee Stock Purchase Plan (the Purchase Plan) and stock options. Stock-based compensation expense is measured at the grant date, based on the fair value of the awards, and is recognized as expense over the requisite service period only for those equity awards expected to vest.

The fair value of the RSUs is determined based on the stock price on the date of grant. The fair value of the RSUs is amortized on a straight-line basis over the requisite service period of the awards, which is generally three to four years. We estimated the fair value of stock purchased under our Purchase Plan and stock options using the Black-Scholes model. This model utilizes the estimated fair value of common stock and requires that, at the date of grant, we use the expected term of the grant, the expected volatility of the price of our common stock, risk-free interest rates and expected dividend yield of our common stock. The fair value is amortized on a straight-line basis over the requisite service periods of the awards, which is generally three to four years for stock options, and six months to two years for stock purchased under our Purchase Plan.

The expected term represents the period that stock options are expected to be outstanding. We estimated the expected term based on historical exercise patterns and post vesting termination behavior. We estimated the expected volatility of stock options using a blended historical and implied volatility data. The computation of expected volatility for the Purchase Plan is based on our historical volatility.

Compensation costs are recognized only for those equity awards expected to vest. These compensation costs are determined at the aggregate grant level for service-based awards and at the individual vesting tranche level for awards with performance conditions.

Business Combinations

In our business combinations, we are required to recognize all the assets acquired, liabilities assumed, contractual contingencies, and contingent consideration at their fair value on the acquisition date. Further, acquisition-related costs are recognized separately from the acquisition and expensed as incurred; restructuring costs are generally expensed in periods subsequent to the acquisition date; changes in the estimated fair value of contingent consideration after the initial measurement on the acquisition date are recognized in earnings in the period of the change in estimate; and changes in accounting for deferred tax asset valuation allowances and acquired income tax uncertainties after the measurement period are recognized as a component of provision for (benefit from) income taxes. In addition, the fair value of in-process research and development (R&D) is recorded as an indefinite-lived intangible asset until the underlying project is completed, at which time the intangible asset is amortized over its estimated useful life, or abandoned, at which time the intangible asset is expensed.

Accounting for business combinations requires management to make significant estimates and assumptions, including the acquisition date fair value of intangible assets, estimated contingent consideration payments and pre-acquisition contingencies.

Although we believe the assumptions and estimates we have made have been reasonable and appropriate, they are based in part on historical experience and information obtained from management of the acquired company and are inherently uncertain. Examples of critical estimates in accounting for acquisitions include but are not limited to:

•

the estimated fair value of the acquisition-related contingent consideration, which is performed using a probability-weighted discounted cash flow model based upon the forecasted achievement of post-acquisition bookings targets;

•

the future expected cost to develop the in-process R&D into commercially viable products and the estimated cash flows from the products when completed;

•

the future expected cash flows from product sales, support agreements, consulting contracts, other customer contracts and acquired developed technologies and patents; and

•

the discount rates.

Unanticipated events and circumstances may occur which may affect the accuracy or validity of such assumptions, estimates or actual results.

Accounting for Income Taxes

We use the asset and liability method of accounting for income taxes. Under this method, income tax expenses or benefits are recognized for the amount of taxes payable or refundable for the current year and for deferred tax liabilities and assets for the expected tax consequences of temporary differences between the tax bases of assets and liabilities for financial reporting purposes and amounts recognized for income tax purposes. The measurement of current and deferred tax assets and liabilities are based on provisions of currently enacted tax laws. The effects of future changes in tax laws or rates are not contemplated.

As part of the process of preparing our consolidated financial statements, we are required to estimate our income tax expense and tax contingencies in each of the tax jurisdictions in which we operate. This process involves estimating current income tax expense together with assessing temporary differences in the treatment of items for tax purposes versus financial accounting purposes that may create net deferred tax assets and liabilities. We rely on estimates and assumptions in preparing our income tax provision.

We consider many factors when assessing the likelihood of future realization of our deferred tax assets, including our recent earnings experience by jurisdiction, expectations of future taxable income, and the carryforward periods available to us for tax reporting purposes, as well as other relevant factors. We establish a valuation allowance to reduce deferred tax assets to the amount we believe is more likely than not to be realized. Due to inherent complexities arising from the nature of our businesses, future changes in income tax law, or variances between our actual and anticipated operating results, we make certain judgments and estimates. Therefore, actual income taxes could materially vary from these estimates.

As part of our accounting for business combinations, a portion of the purchase price was allocated to goodwill and intangible assets. Amortization expenses associated with acquired intangible assets are generally not tax deductible; however, deferred taxes have been recorded for non-deductible amortization expenses as a part of the purchase price allocation. In the event of an impairment charge associated with goodwill, such charges are generally not tax deductible and would increase the effective tax rate in the quarter any impairment is recorded.

We are subject to periodic audits by the Internal Revenue Service and other taxing authorities. These audits may challenge certain tax positions we have taken, such as the timing and amount of deductions and allocation of taxable income to the various tax jurisdictions. The accounting for income tax contingencies may require significant management judgment in estimating final outcomes. Actual results could differ materially from these estimates and could significantly affect the effective tax rate and cash flows in future years. We have elected to record interest and penalties in the financial statements as a component of income taxes.

Concentrations of Risk

Financial instruments that are potentially subject to concentrations of credit risk consist primarily of cash, cash equivalents, marketable securities, and trade receivables. Investment policies have been implemented that limit investments to investment grade securities. The average portfolio maturity is currently less than a year. The risk with respect to trade receivables is mitigated by credit evaluations we perform on our customers and by the diversification of our customer base. One value-added distributor (VAD), Arrow Electronics, Inc. (Arrow) accounted for 16% of our trade receivables balance at December 31, 2014. One VAD, Avnet Inc. (Avnet), and one service provider partner, Orange Business Services, accounted for 17% and 13% of our trade receivables balance as of December 31, 2013, respectively. Two VADs, Arrow and Avnet, represented 20% and 14%, respectively, of our revenue for the year ended December 31, 2014; 18% and 13%, respectively, of our revenue for the year ended December 31, 2013; and 17% and 11% of our revenue for the year ended December 31, 2012.

We outsource the production of our inventory to third-party manufacturers. We rely on purchase orders or long-term contracts with our contract manufacturers. At December 31, 2014, we had no long-term contractual commitment with any manufacturer; however, we did have 90 day commitments totaling $11.0 million.

Changes in Accumulated Other Comprehensive Income (Loss)

Comprehensive income (loss) is defined as the change in equity during a period from transactions and other events and circumstances from non-owner sources. We include comprehensive income (loss) as part of our consolidated statement of changes in stockholders' equity, the components of which are included in the Statement of Comprehensive Income (Loss). Accumulated other comprehensive income (loss) includes net unrealized gains (losses) on available-for-sale securities, unrealized gains (losses) on derivative instruments that qualify for hedge accounting, and net foreign currency translation gains (losses).

The amounts reclassified out of Accumulated other comprehensive income (loss) to Net income (loss) are as follows:

(in thousands)

Unrealized gain (loss) on investments, net of tax

Foreign currency translation adjustment

Derivative instruments gain, net of tax

Total

Balance as of December 31, 2013

$

(30

)

$

(59

)

$

505

$

416

Other comprehensive loss before reclassifications

(74

)

(2,144

)

(4,890

)

(7,108

)

Amounts reclassified from accumulated other comprehensive income (loss)

30

—

998

1,028

Net current-period other comprehensive loss

(44

)

(2,144

)

(3,892

)

(6,080

)

Balance at December 31, 2014

$

(74

)

$

(2,203

)

$

(3,387

)

$

(5,664

)

Amounts reclassified from Accumulated other comprehensive income (loss) to Net income (loss) for unrealized gains (losses) on investments are recorded in Interest expense and other, net. Amounts reclassified from Accumulated other comprehensive income (loss) to Net income (loss) for derivatives instrument gains (losses) are recorded in Cost of support and services and Operating expenses.

Foreign Currency Translation

While the majority of our revenue contracts are denominated in U.S. dollars, we incur certain operating expenses in various foreign currencies. The functional currency of our foreign operations is generally the local country’s currency. Consequently, expenses of operations outside the U.S. are translated into U.S. dollars using average exchange rates for the period reported while assets and liabilities of operations outside the U.S. are translated into U.S. dollars using end of period exchange rates. Foreign currency translation adjustments not affecting net income (loss) are included in stockholders’ equity as a component of Accumulated other comprehensive income (loss) in the accompanying consolidated balance sheets. The revaluation effect of foreign currency fluctuations on intercompany balances is recorded to foreign currency gain (loss) and included in Interest expense and other, net in the accompanying consolidated statements of operations. Foreign currency gains (losses) included in Interest expense and other, net included for the years ended December 31, 2014, 2013 and 2012, were a loss of $1.3 million, a gain of $0.1 million and a loss of $2.6 million, respectively.

Advertising

Advertising costs are expensed as incurred. Adverting expenses recorded as marketing expenses were $1.7 million, $2.6 million and $3.6 million for the years ended December 31, 2014, 2013 and 2012, respectively.

Cooperative advertising obligations with customers are accrued and the costs expensed at the time the related revenue is recognized. Cooperative advertising expenses are recorded as marketing expenses to the extent that an advertising benefit separate from the revenue transaction can be identified and the cash paid does not exceed the fair value of that advertising benefit received. Otherwise, such cooperative advertising obligations with customers are recorded as a reduction of revenue. Cooperative advertising expenses recorded as a reduction of revenue were $5.4 million, $6.5 million and $6.5 million in the years ended December 31, 2014, 2013 and 2012, respectively.

Research and Development

All costs to develop our products are expensed as incurred.

Shipping and Handling Costs

Our shipping and handling costs for product sales are included in the cost of product revenue for all periods presented.

Recent Accounting Pronouncements

In April 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2014-08, Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity, to change the criteria for determining which disposals can be presented as discontinued operations and to enhance the related disclosure requirements for discontinued operations. We early adopted ASU 2014-08 in our fourth quarter of 2014 and applied the new guidance in accounting for the sale of our SteelStore and SteelApp product lines. We determined that the sale of the SteelStore product line and our plan to sell the SteelApp product line did not represent strategic shifts that have or will have a major effect on our operations and financial results, and accordingly neither was reported as a discontinued operation.

In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers, which amends the existing accounting standards for revenue recognition. ASU 2014-09 is based on principles that govern the recognition of revenue at an amount an entity expects to be entitled when products are transferred to customers. ASU 2014-09 will be effective for the Company beginning in its first quarter of 2017. Early adoption is not permitted. The new revenue standard may be applied retrospectively to each prior period presented or retrospectively with the cumulative effect recognized as of the date of adoption. The Company is currently evaluating the impact of adopting the new revenue standard on its consolidated financial statements.

In June 2014, the FASB issued ASU No. 2014-12, Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period. ASU 2014-12 requires that a performance target that affects vesting and could be achieved after the requisite service period be treated as a performance condition. A reporting entity should apply existing guidance in Accounting Standards Codification (ASC) 718, Compensation Stock Compensation (ASC 718), as it relates to such awards. ASU 2014-12 is effective for us in our first quarter of fiscal 2017 with early adoption permitted using either of two methods: (i) prospective to all awards granted or modified after the effective date; or (ii) retrospective to all awards with performance targets that are outstanding as of the beginning of the earliest annual period presented in the financial statements and to all new or modified awards thereafter, with the cumulative effect of applying ASU 2014-12 as an adjustment to the opening retained earnings balance as of the beginning of the earliest annual period presented in the financial statements. We are currently evaluating the impact, if any, of our pending adoption on ASU 2014-12 on our consolidated financial statements.

In July 2013, the FASB released ASU No. 2013-11, Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists. ASU No. 2013-11 requires that an unrecognized tax benefit should be presented as a reduction of a deferred tax asset for a net operating loss carryforward or other tax credit carryforward when settlement in this manner is available under the tax law. We are required to adopt this standard starting fiscal year 2015 and are currently in the process of determining the impact, if any, on our consolidated financial statements.

Acquisitions

Acquisitions	12 Months Ended
	Dec. 31, 2014
Business Combinations [Abstract]
Discontinued Operations	Fiscal 2014 Dispositions
	SteelStore product line
	On October 27, 2014, we sold our SteelStore product line to NetApp, Inc. (NetApp) for $80.0 million. The Company received $65.8 million in cash, while approximately $12.0 million was held in escrow. The amount held in escrow, which is classified as Other assets on the Consolidated Balance Sheets was appropriately excluded from the proceeds from the sale of assets line on the Consolidated Statement of Cash Flows. The Company disposed of $21.0 million in net assets, which included the write-off of $19.4 million of goodwill related to the SteelStore product line. We recognized a gain of $57.4 million in Other income (expense), net. The revenues and costs of this product line are included in our results of operations through October 27, 2014. Revenues from the SteelStore product line were $4.6 million, $4.4 million, and $2.0 million in the years ended December 31, 2014, 2013 and 2012, respectively.
	Fiscal 2014 Assets and Liabilities Held for Sale
	SteelApp product line
	Pursuant to our announced intention to seek strategic options, on February 4, 2015, we entered into a definitive agreement with Brocade Communication Systems, Inc. (Brocade) for the sale of our SteelApp product line. At December 31, 2014 we have classified the SteelApp related fixed assets, net, of $1.4 million, intangible assets, net, of $14.4 million, and goodwill of $15.2 million as Assets held for sale and deferred revenue of $9.6 million as Liabilities held for sale in our consolidated balance sheet. Revenues from the sale of the SteelApp products and services to be divested were $31.1 million, $35.8 million, and $28.4 million in 2014, 2013, and 2012, respectively.
Acquisitions	ACQUISITIONS AND DISPOSITIONS
	Fiscal 2014 Dispositions
	SteelStore product line
	On October 27, 2014, we sold our SteelStore product line to NetApp, Inc. (NetApp) for $80.0 million. The Company received $65.8 million in cash, while approximately $12.0 million was held in escrow. The amount held in escrow, which is classified as Other assets on the Consolidated Balance Sheets was appropriately excluded from the proceeds from the sale of assets line on the Consolidated Statement of Cash Flows. The Company disposed of $21.0 million in net assets, which included the write-off of $19.4 million of goodwill related to the SteelStore product line. We recognized a gain of $57.4 million in Other income (expense), net. The revenues and costs of this product line are included in our results of operations through October 27, 2014. Revenues from the SteelStore product line were $4.6 million, $4.4 million, and $2.0 million in the years ended December 31, 2014, 2013 and 2012, respectively.
	Fiscal 2014 Assets and Liabilities Held for Sale
	SteelApp product line
	Pursuant to our announced intention to seek strategic options, on February 4, 2015, we entered into a definitive agreement with Brocade Communication Systems, Inc. (Brocade) for the sale of our SteelApp product line. At December 31, 2014 we have classified the SteelApp related fixed assets, net, of $1.4 million, intangible assets, net, of $14.4 million, and goodwill of $15.2 million as Assets held for sale and deferred revenue of $9.6 million as Liabilities held for sale in our consolidated balance sheet. Revenues from the sale of the SteelApp products and services to be divested were $31.1 million, $35.8 million, and $28.4 million in 2014, 2013, and 2012, respectively.
	Fiscal 2012 Acquisitions
	OPNET Technologies, Inc.
	On December 18, 2012, we completed our acquisition of OPNET Technologies, Inc. (OPNET) by means of a merger of one of our wholly-owned subsidiaries with and into OPNET such that OPNET became a wholly owned subsidiary of Riverbed. The addition of OPNET's broad-based family of Application Performance Management (APM) products enhances our position in the Network Performance Management (NPM) market and enables us to provide customers with an integrated solution that both monitors network and application performance and also accelerates it. We included the financial results of OPNET in our consolidated financial statements from the acquisition date.
	The total purchase price for OPNET was approximately $980.2 million, which was comprised of a cash payment of $857.0 million, the fair value of Riverbed common stock issued of $122.6 million, and the fair value of stock options assumed of $0.6 million. In allocating the total purchase price based on estimated fair values as of the acquisition date, we initially recorded $582.2 million of goodwill, $458.5 million of identifiable intangible assets, $159.3 million of net deferred tax liabilities, and $98.8 million of net other tangible assets. In determining the final purchase price allocation, adjustments were recorded to goodwill, net deferred tax liabilities and net other tangible assets. The final purchase price allocation as of December 31, 2013 was $586.7 million of goodwill, $458.5 million of identifiable intangible assets, $166.1 million of net deferred tax liabilities, and $101.1 million of net other tangible assets.
	Acquisition and Disposition-related Costs
	Acquisition and disposition-related costs include transaction costs, integration and acquisition-related costs and changes in the fair value of the acquisition-related contingent consideration. Transaction costs include professional services fees paid to investment bankers, legal, accounting, and similar service providers. Transaction costs in the year ended December 31, 2014 include $9.9 million related to the Merger. Integration and acquisition-related costs include employee termination benefits, other acquired employee related retention costs, facilities exit and rationalization costs, integration related professional services, and the write-down of certain acquired in-progress research and development intangibles.
	The following table summarizes the acquisition- and disposition-related costs recognized in Other costs in the consolidated statements of operations:
		Year ended December 31,
	(in thousands)	2014		2013		2012
	Transaction costs	$	10,992	$	—	$	12,504
	Integration and acquisition-related costs	5,688		18,322		3,412
	Change in fair value of acquisition-related contingent consideration	—		—		(15,190		)
	Acquisition and disposition-related costs	$	16,680	$	18,322	$	726
	The following table shows the acquisition-related compensation costs that were recognized in operating expenses in the years 2014, 2013 and 2012:
	(in thousands)	Year ended December 31,
		2014		2013		2012
	Sales and marketing	$	3	$	486	$	788
	Research and development	99		98		1,807
	General and administrative	—		566		23
	Total acquisition-related compensation costs	102		1,150		2,618
	Acquisition and integration-related recorded in Other costs	16,680		18,322		726
	Total acquisition and disposition-related costs	$	16,782	$	19,472	$	3,344

Net_Income_Per_Common_Share

Net Income Per Common Share	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Net Income Per Common Share	NET INCOME (LOSS) PER COMMON SHARE
	Basic net income (loss) per common share is computed by dividing net income (loss) by the weighted average number of common shares outstanding during the period. Diluted net income (loss) per common share is computed by giving effect to all potential dilutive common shares, including stock awards.
	The following table sets forth the computation of net income (loss) per share:
	(in thousands, except per share data)	Year ended December 31,
		2014			2013			2012
	Net income (loss)	$	71,268		$	(12,418	)	$	54,597
	Weighted average common shares outstanding — basic	158,680			162,707			156,205
	Dilutive effect of employee stock plans	4,512			—			8,365
	Weighted average common shares outstanding — diluted	163,192			162,707			164,570
	Basic net income (loss) per share	$	0.45		$	(0.08	)	$	0.35
	Diluted net income (loss) per share	$	0.44		$	(0.08	)	$	0.33
	Stock options outstanding with an exercise price higher than our average stock price for the periods presented, represent out-of-the-money awards and the anti-dilutive effect of other stock awards are excluded from the calculations of the diluted net income (loss) per common share since the effect would have been anti-dilutive under the treasury stock method.
	In addition, stock options and other stock awards outstanding with an exercise price lower than our average stock price for the periods presented, representing in-the-money awards that would otherwise have a dilutive effect under the treasury stock method, are excluded from the calculations of the diluted loss per common share in periods with a loss since the effect in such periods would have been anti-dilutive.
	The following weighted average outstanding shares of common stock from stock options and other awards options were excluded from the computation of diluted net income (loss) per common share for the periods presented because including them would have had an anti-dilutive effect:
	(in thousands)	Year ended December 31,
		2014		2013			2012
	Total potential shares of common stock	12,557		21,717			10,368

Fair_Value_Of_Assets_And_Liabi

Fair Value Of Assets And Liabilites	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair Value Of Assets And Liabilites	IR VALUE OF ASSETS AND LIABILITIES
	As of December 31, 2014, the fair value of our cash, cash equivalents, investments, derivative assets and liabilities, and borrowings measured on a recurring basis consisted of the following:
	(in thousands)	Total		Level 1		Level 2
	Assets:
	Corporate bonds and notes	$	24,637	$	—	$	24,637
	U.S. government-sponsored enterprise obligations	27,548		—		27,548
	Money market funds	28,283		28,283		—
	Cash	215,916		—		—
	Total cash and cash equivalents	$	296,384	$	28,283	$	52,185
	Corporate bonds and notes	$	75,845	$	—	$	75,845
	U.S. government backed securities	43,736		43,736		—
	U.S. government-sponsored enterprise obligations	178,287		—		178,287
	FDIC-backed certificates of deposit	19,654		—		19,654
	Total investments	$	317,522	$	43,736	$	273,786
	Total assets	$	613,906	$	72,019	$	325,971
	Liabilities:
	Derivative liability	$	2,298	$	—	$	2,298
	Borrowings	$	510,000	$	—	$	510,000
	Total liabilities	$	512,298	$	—	$	512,298
	As of December 31, 2014 and 2013, there were no Level 3 instruments.
	As of December 31, 2013, the fair value measurements of our cash and cash equivalents, investments, derivative assets and liabilities, and borrowings consisted of the following:
	(in thousands)	Total		Level 1		Level 2
	Assets:
	Corporate bonds and notes	$	28,545	$	—	$	28,545
	U.S. government-sponsored enterprise obligations	18,775		—		18,775
	Money market funds	30,009		30,009		—
	Cash	130,693		—		—
	Total cash and cash equivalents	$	208,022	$	30,009	$	47,320
	Corporate bonds and notes	$	74,648	$	—	$	74,648
	U.S. government backed securities	23,210		23,210		—
	U.S. government-sponsored enterprise obligations	211,094		—		211,094
	FDIC-backed certificates of deposit	15,062		—		15,062
	Total investments	$	324,014	$	23,210	$	300,804
	Derivative asset	$	331	$	—	$	331
	Total assets	$	532,367	$	53,219	$	348,455
	Liabilities:
	Derivative liability	$	103	$	—	$	103
	Borrowings	$	525,000	$	—	$	525,000
	Total liabilities	$	525,103	$	—	$	525,103
	The following tables present the gross unrealized gains and losses as of December 31, 2014 and 2013:
	(in thousands)	Fair Value		Unrealized		Unrealized
				Gains		Losses
	Corporate bonds and notes	$	100,482	$	—	$	(16	)
	U.S. government backed securities	43,736		4		(29		)
	U.S. government-sponsored enterprise obligations	205,835		16		(103		)
	Total investments at December 31, 2014	$	350,053	$	20	$	(148	)
	Corporate bonds and notes	$	103,193	$	1	$	(24	)
	U.S. government backed securities	23,210		7		(2		)
	U.S. government-sponsored enterprise obligations	229,869		55		(30		)
	FDIC-backed certificates of deposit	15,062		1		—
	Total investments at December 31, 2013	$	371,334	$	64	$	(56	)
	We regularly review our investment portfolio to determine if any security is other-than-temporarily impaired, which would require us to record an impairment charge in the period any such determination is made. In making this judgment, we evaluate, among other things, the duration and extent to which the fair value of a security is less than its cost; the financial condition of the issuer and any changes thereto; and our intent and ability to sell, or whether we will more likely than not be required to sell, the security before recovery of its amortized cost basis. We have evaluated our investments as of December 31, 2014 and have determined that no investments with unrealized losses are other-than-temporarily impaired. No investments have been in a continuous loss position greater than one year.
	Cash, Cash Equivalents and Investments
	Cash and cash equivalents consist primarily of highly liquid investments in money market mutual funds, government-sponsored enterprise obligations, treasury bills, commercial paper and corporate bonds and notes with remaining maturities at date of purchase of 90 days or less. The carrying value of cash and cash equivalents at December 31, 2014 and 2013 was $296.4 million and $208.0 million, respectively. The carrying value approximates fair value at December 31, 2014 and 2013.
	Investments, which are classified as available for sale at December 31, 2014, are carried at fair value, with the unrealized gains and losses, net of tax, reported in Accumulated other comprehensive income (loss) in stockholders’ equity. Investments consist of government-sponsored enterprise obligations, municipal bonds, treasury bills, FDIC-backed certificates of deposit, commercial paper and corporate bonds and notes. The fair value of our investments is determined as the exit price in the principal market in which we would transact. Level 1 instruments are valued based on quoted market prices in active markets and include treasury bills and money market funds. Level 2 instruments are valued based on quoted prices in markets that are not active, broker or dealer quotations, or alternative pricing sources with reasonable levels of price transparency and include commercial paper, corporate bonds and notes, municipal bonds, government-sponsored enterprise obligations and FDIC-backed certificates of deposit. Level 3 instruments are valued based on unobservable inputs that are supported by little or no market activity and reflect our own assumptions in measuring fair value. Generally our investments have maturity dates up to two years from our date of purchase and active markets for these investments exist.
	Restricted Cash
	Restricted cash primarily represents the $12.0 million escrow from the sale of our SteelStore product line and collateralized letters of credit established in connection with lease agreements for our facilities. Current restricted cash totaled $1.6 million and $3.3 million as of December 31, 2014 and 2013, respectively. Current restricted cash is included in Prepaid expenses and other current assets in the consolidated balance sheet. Long-term restricted cash totaled $20.6 million and $9.1 million at December 31, 2014 and 2013, respectively. Long-term restricted cash is included in Other assets in the consolidated balance sheets and consists primarily of funds held in escrow related to the sale of our SteelStore product line and as collateral for letters of credit for the security deposit on the certain leases.
	Fair Value of Derivative Instruments
	We use derivative instruments to partially offset our market exposures to fluctuations in certain foreign currency exchange rates, which exist as part of ongoing business operations. These derivatives are considered Level 2 instruments. Derivative assets are included in Prepaid expenses and other current assets in the consolidated balance sheet. Derivative liabilities are included in Other accrued liabilities in the consolidated balance sheet. Refer to Note 13 - Derivative Financial Instruments for additional derivative financial instrument disclosure.
	Borrowings
	Our borrowings are classified as short-term and long-term and are considered Level 2 instruments. The fair value of these borrowings has been valued using an estimate of the interest rate that we would be required to pay on the issuance of debt with similar terms and discounting the cash flows at that rate. Refer to Note 14 - Borrowings for the carrying value and additional disclosures on our borrowings.

Inventory

Inventory	12 Months Ended
	Dec. 31, 2014
Inventory, Gross [Abstract]
Inventory	INVENTORY
	Inventories consist primarily of hardware and related component parts and evaluation units located at customer locations, and are stated at the lower of cost (on a first-in, first-out basis) or market. Inventory is comprised of the following:
	(in thousands)	As of December 31,
		2014		2013
	Raw materials	$	2,387	$	5,069
	Finished goods	11,587		15,430
	Evaluation units	812		4,526
	Total	$	14,786	$	25,025

Goodwill_And_Intangible_Assets

Goodwill And Intangible Assets	12 Months Ended
	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill And Intangible Assets	GOODWILL AND INTANGIBLE ASSETS
	Goodwill
	Goodwill represents the excess of the purchase price of an acquired business over the fair value of the underlying net tangible and intangible assets. We consider the acquired businesses as additions to our product portfolio. We record goodwill adjustments pursuant to changes to net assets acquired during the measurement period, which is up to one year from the date of acquisition. A portion of the goodwill associated with the acquisition of OPNET, Expand, Global Protocols, LLC, Zeus and Aptimize will be deductible for income tax purposes.
	Goodwill consisted of the following:
	(in thousands)
	Balance at December 31, 2012	$	699,785
	Other adjustments	4,520
	Balance at December 31, 2013	$	704,305
	Disposition of goodwill related to the sale of the SteelStore product line	(19,368		)
	Reclassification to Assets held for sale	(15,221		)
	Balance at December 31, 2014	$	669,716
	Intangible Assets
	Intangible assets are recorded at their estimated fair value as of the acquisition date of the related acquired business. Intangible assets that have a finite life are amortized over their useful lives.
	Intangible assets, net, consisted of the following:
	(in thousands)		As of December 31, 2014
			Gross				Accumulated				Net
							Amortization
	Existing technology		$	205,453			$	(92,765	)		$	112,688
	Patents		3,299				(3,049		)		250
	Maintenance agreements		216,800				(63,103		)		153,697
	Customer contracts		49,603				(20,679		)		28,924
	Trademarks		12,500				(5,181		)		7,319
	Non-compete agreements		5,300				(3,634		)		1,666
	Currency translation adjustment		—				—				—
	Total intangible assets, net		$	492,955			$	(188,411	)		$	304,544
	Intangible Assets to be disposed of were included in Assets held for sale on the consolidated balance sheet as of December 31, 2014 and, accordingly, were not included in the table above. The amortization of these intangible assets ceased as of the date they were deemed to be held for sale. Accordingly, our intangible assets as of December 31, 2014 were recorded as:
	(in thousands)
	Intangibles, net		$	304,544
	Assets held for sale		14,386
	Total intangibles assets		$	318,930
			Weighted Average Useful Life		As of December 31, 2013
					Gross				Accumulated				Net
									Amortization
	Existing technology		5.4 years		$	237,353			$	(73,111	)		$	164,242
	Patents		5.1 years		8,799				(5,414		)		3,385
	Maintenance agreements		7.4 years		230,100				(41,353		)		188,747
	Customer contracts		6.3 years		51,103				(13,737		)		37,366
	Trademarks		5.6 years		12,800				(3,561		)		9,239
	Non-compete agreements		3.0 years		5,300				(1,900		)		3,400
	Currency translation adjustment		N/A		—				—				(1,912		)
	Total intangible assets, net				$	545,455			$	(139,076	)		$	404,467
	Amortization expense was $85.5 million, $103.0 million and $25.9 million for the years ended December 31, 2014, 2013 and 2012, respectively.
	Estimated future amortization expense related to the above intangible assets subject to amortization, excluding those intangibles recorded as Assets held for sale, at December 31, 2014 is as follows:
	Fiscal Year		In thousands
	2015		$	71,609
	2016		68,337
	2017		59,013
	2018		57,795
	2019		27,040
	Thereafter		20,750
	Total remaining amortization of intangibles		$	304,544

Fixed_Assets

Fixed Assets	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Fixed Assets	FIXED ASSETS
	Fixed assets are stated at cost. Depreciation is calculated using the straight-line method over the estimated useful lives of the respective assets, which is typically two to five years. Leasehold improvements are amortized using the straight-line method over the shorter of the lease term or estimated useful life of the asset. Repair and maintenance costs are expensed as incurred.
	Fixed assets consisted of the following:
	(in thousands)	Estimated	As of December 31,
		Useful
		Lives	2014			2013
	Computer hardware and equipment	3 years	$	53,595		$	53,417
	Leasehold improvements	2-5 years	48,840			37,733
	Furniture and fixtures	3-5 years	14,871			10,207
	Software	2-5 years	48,061			38,173
	Total fixed assets		165,367			139,530
	Accumulated depreciation and amortization		(94,567		)	(81,720		)
	Fixed assets, net		$	70,800		$	57,810
	Property and equipment of approximately $1.4 million to be disposed of were included in Assets held for sale on the consolidated balance sheet as of December 31, 2014 and, accordingly, were not included in the table above. Depreciation and amortization of these assets ceased as of the date they were deemed to be held for sale.
	Depreciation and amortization expense of fixed assets was $28.2 million, $23.2 million and $14.6 million for the years ended December 31, 2014, 2013 and 2012, respectively.

Accrued_Liabilities

Accrued Liabilities	12 Months Ended
	Dec. 31, 2014
Accrued Liabilities, Current [Abstract]
Accrued Liabilities	ACCRUED LIABILITIES
	Current liabilities
	Accrued compensation and benefits consisted of the following:
	(in thousands)	As of December 31,
		2014		2013
	Accrued commissions	$	12,428	$	14,850
	Vacation liability	$	15,089	$	14,218
	Other accrued compensation and benefits	21,223		22,920
	Total accrued compensation and benefits	$	48,740	$	51,988
	Other accrued liabilities consisted of the following:
	(in thousands)	As of December 31,
		2014		2013
	Deferred rent liability	$	36,119	$	12,342
	Other accrued liabilities	26,016		24,178
	Total other accrued liabilities	$	62,135	$	36,520
	Other long-term liabilities
	Other long-term liabilities consisted of the following:
	(in thousands)	As of December 31,
		2014		2013
	Other long-term liabilities	$	1,622	$	445
	Unrecognized tax benefit obligation	45,713		48,465
	Total other long-term liabilities	$	47,335	$	48,910

Deferred_Revenue

Deferred Revenue	12 Months Ended
	Dec. 31, 2014
Deferred Revenue [Abstract]
Deferred Revenue	DEFERRED REVENUE
	Deferred revenue consisted of the following:
	(in thousands)	As of December 31,
		2014		2013
	Product	$	40,547	$	58,692
	Support and services	283,191		253,783
	Total deferred revenue	$	323,738	$	312,475
	Reported as:
	Deferred revenue, current	$	219,600	$	217,131
	Liabilities held for sale	9,586		—
	Deferred revenue, non-current	94,552		95,344
	Total deferred revenue	$	323,738	$	312,475
	Deferred revenue of approximately $9.6 million to be disposed of was included in Liabilities held for sale on the consolidated balance sheet as of December 31, 2014 and, accordingly, was not included in the table above. Amortization ceased as of the date the deferred revenue was deemed to be held for sale.
	Deferred product revenue relates to arrangements where not all revenue recognition criteria have been met. Deferred support revenue represents customer payments made in advance for support contracts. Support contracts are typically billed on a per annum basis in advance and revenue is recognized ratably over the support period.

Restructuring_Notes

Restructuring (Notes)	12 Months Ended
	Dec. 31, 2014
Restructuring and Related Activities [Abstract]
Restructuring	RESTRUCTURING
	As of December 31, 2014, current and non-current restructuring liabilities were $3.6 million and consisted of obligations under excess facility operating leases, net of projected future sublease receipts, and one-time employee termination benefits, as shown in the table below.
	During 2013, we recorded facilities exit costs of $1.9 million related to rationalizing and exiting certain redundant facilities obtained in the OPNET acquisition. During 2014, we recorded restructuring charges of $5.2 million. The restructuring charges included excess facilities charges of $0.9 million, and one-time employee termination benefits of $4.3 million related to a reduction in total staff during the fourth quarter of 2014 of approximately 80 people, or 3% of the total workforce. The restructuring plan was completed in the fourth quarter of 2014, therefore additional charges are not anticipated.
	Restructuring liabilities, recorded in Other costs on the consolidated statements of operations, consisted of (in thousands):
		Termination Benefits			Excess Facilities			Total
	Balance at December 31, 2012	$	—		$	—		$	—
	Charges in 2013	—			1,873			1,873
	Cash payments	—			(45		)	(45		)
	Balance at December 31, 2013	—			1,828			1,828
	Charges in 2014	4,333			1,113			5,446
	Cash payments	(3,018		)	(682		)	(3,700		)
	Balance at December 31, 2014	$	1,315		$	2,259		$	3,574
	As reported in (in thousands) as of December 31, 2014:
		Termination Benefits			Excess Facilities			Total
	Other accrued liabilities	$	1,315		$	1,359		$	2,674
	Other long-term liabilities	—			900			900
	Total restructuring liability	$	1,315		$	2,259		$	3,574

Guarantees

Guarantees	12 Months Ended
	Dec. 31, 2014
Guarantees [Abstract]
Guarantees	GUARANTEES
	Our agreements with customers, as well as our channel partner agreements, generally include certain provisions for indemnifying customers and channel partners and their affiliated parties against liabilities if our products infringe a third party’s intellectual property rights or for other mutually agreed upon liabilities. To date, we have not incurred any material costs as a result of such indemnifications and have not accrued any liabilities related to such obligations in our consolidated financial statements.
	As permitted or required under Delaware law and to the maximum extent allowable under that law, we have certain obligations to indemnify our officers, directors and certain key employees for certain events or occurrences while the officer, director or employee is or was serving at our request in such capacity. These indemnification obligations are valid as long as the director, officer or employee acted in good faith and in a manner the person reasonably believed to be in or not opposed to the best interests of the corporation, and, with respect to any criminal proceeding, had no reasonable cause to believe his or her conduct was unlawful. The maximum potential amount of future payments we could be required to make under these indemnification obligations is unlimited; however, we have a director and officer insurance policy that mitigates our exposure and enables us to recover a portion of any future amounts paid.

Lease_Commitments

Lease Commitments	12 Months Ended
	Dec. 31, 2014
Leases [Abstract]
Lease Commitments	LEASE COMMITMENTS
	We lease our facilities under non-cancelable operating lease agreements. Future minimum commitments for these operating leases in place as of December 31, 2014 with a remaining non-cancelable lease term in excess of one year are as follows:
	(in thousands)	31-Dec-14
	2015	$	28,634
	2016	27,145
	2017	25,303
	2018	23,645
	2019	21,328
	Thereafter	72,249
	Total	$	198,304
	The terms of certain lease agreements provide for rental payments on a graduated basis. We recognize rent expense on the straight-line basis over the lease period and have accrued for rent expense incurred but not paid. Rent expense under operating leases was $27.8 million, $22.5 million and $13.6 million for the years ended December 31, 2014, 2013 and 2012, respectively.

Derivative_Financial_Instrumen

Derivative Financial Instruments	12 Months Ended
	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	DERIVATIVE FINANCIAL INSTRUMENTS
	We use derivative instruments to partially offset our market exposures to fluctuations in certain foreign currency exchange rates, which exist as part of ongoing business operations. Our general practice is to hedge a majority of transaction exposures denominated in British pounds, Euros, Australian dollars and Singapore dollars. These instruments have maturities up to twelve months in the future. We do not enter into derivative instrument transactions for trading or speculative purposes.
	Foreign currency contracts designated as cash flow hedges
	We utilize foreign currency forward contracts to hedge certain forecasted foreign currency transactions relating to cost of service and operating expense. These contracts are designated and documented as cash flow hedges at their inception. All changes in time value are excluded from the cash flow hedge and recorded to Interest expense and other, net in the period incurred. The effective portion of derivative's gains or losses on these hedges is initially included in Accumulated other comprehensive income (loss) and is subsequently reclassified into the cost of service or operating expense, to which the hedged transaction relates, upon the occurrence of the forecasted transaction. We record any ineffectiveness of the hedging instruments in Interest expense and other, net in our consolidated financial statements in the period incurred. No ineffectiveness was recorded during the years ended December 31, 2014 and 2013.
	The notional amount of these contracts was $71.4 million at December 31, 2014 and $49.0 million at December 31, 2013. Outstanding contracts are recognized as either assets or liabilities on the balance sheet at fair value. The amount remaining in Accumulated other comprehensive income (loss) as of December 31, 2014 was not significant and is expected to be recognized into earnings within the next twelve months.
	Derivatives not designated as hedging instruments
	We use foreign currency forward contracts to reduce the variability in gains and losses generated from the re-measurement of certain monetary assets and liabilities denominated in foreign currencies. These hedges do not qualify for hedge accounting treatment. These derivatives are carried at fair value with gains and losses recognized as Interest expense and other, net. Changes in the fair value of the derivatives are largely offset within the consolidated statement of operations by re-measurement of the underlying assets and liabilities. We had a notional value of $13.2 million in derivative instruments that were non-designated hedges at December 31, 2014 and $11.7 million at December 31, 2013.
	Fair Value of Derivative Instruments
	The fair value of derivative instruments in our consolidated balance sheets was as follows as of December 31, 2014 and 2013:
		As of December 31,
	(in thousands)	2014			2013
	Derivative assets:
	Foreign currency contracts designated as cash flow hedges	$	—		$	162
	Derivatives not designated as hedging instruments	—			169
	Total derivative assets	$	—		$	331
	Derivative liabilities:
	Foreign currency contracts designated as cash flow hedges	$	1,928		$	57
	Derivatives not designated as hedging instruments	370			46
	Total derivative liabilities	$	2,298		$	103
	The effects of derivatives designated as hedging instruments on our consolidated statements of operations were as follows for the years ended December 31, 2014 and 2013:
		Year ended December 31,
	(in thousands)	2014			2013
	Amount of gain (loss) recognized in Accumulated other comprehensive income (loss) on derivatives (effective portion)	$	(5,095	)	$	191
	Amount and location of losses reclassified from Accumulated other comprehensive income (loss) into earnings (effective portion)
	Cost of support and services	$	(130	)	$	(90	)
	Sales and marketing	(829		)	(154		)
	Research and development	(19		)	(36		)
	General and administrative	(20		)	(29		)
	Total	$	(998	)	$	(309	)
	Amount and location of gain recognized in earnings on derivatives (ineffective portion and amount excluded from effectiveness testing)
	Interest expense and other, net	$	214		$	91
	The effects of derivatives not designated as hedging instruments on our consolidated statements of operations were as follows for the year ended December 31, 2014 and 2013:
		Year ended December 31,
	(in thousands)	2014			2013
	Interest expense and other, net	$	(864	)	$	192
	We enter into master netting arrangements with certain counterparties, which reduce credit risk by permitting net settlement of transactions with the same counterparty. A master netting arrangement may allow counterparties to net settle amounts owed to each other as a result of multiple, separate derivative transactions. These agreements also provide a right to offset corresponding amounts at the option of the non-defaulting party or non-affected party upon the early termination of these agreements by default or upon certain other termination events. For presentation on the consolidated balance sheets, it is our policy to not offset fair value amounts recognized for derivative instruments under master netting arrangements. As of December 31, 2014, we have posted no collateral for derivative instruments, therefore no amounts exist to offset the fair value amounts recognized for derivative instruments under master netting arrangements.

Borrowings

Borrowings	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Borrowings	BORROWINGS
	In December 2013, we entered into a credit agreement and related security and other agreements for a $600.0 million credit facility (the 2013 Credit Facility) providing for a $300.0 million senior secured term credit facility and a $300.0 million senior secured revolving credit facility. The 2013 Credit Facility has a five year term. On December 20, 2013, we drew down $300.0 million in term loans, and $225.0 million under the revolving credit facility. The proceeds were used to pay-off all obligations under the credit agreement and related security and other agreements, dated as of December 18, 2012 (the 2012 Credit Facility), whereby we borrowed $575.0 million to facilitate the acquisition of OPNET. Pursuant to the issuance of the 2013 Credit Facility, we incurred debt issuance costs of approximately $4.2 million, which is recorded as a deferred asset and will be amortized to interest expense using the effective interest rate method.
	Borrowings under the 2013 Credit Facility bear interest based on the daily balance outstanding at LIBOR (with no rate floor) plus an applicable margin (varying from 1.25% to 2.00%) or, in the certain cases a base rate (based on a certain lending institution’s Prime Rate or as otherwise specified in the credit agreement, with no rate floor) plus an applicable margin (varying from 0.25% to 1.00%). The revolving credit facility also carries a commitment fee equal to the unused borrowings multiplied by an applicable margin (varying from 0.25% to 0.30%). The applicable margins are calculated quarterly and vary based on our leverage ratio as set forth in the credit agreement. The initial interest rate on both the term and revolving loans is LIBOR + 175 basis points, or 2.0% as of December 31, 2013. Beginning in 2014, 5% of the initial term loan value is to be paid annually in quarterly installments.
	The term loan contains various customary representations and warranties by us, which include customary use of materiality, material adverse effect and knowledge qualifiers. The 2013 Credit Facility also contains customary affirmative and negative covenants including, among other requirements, negative covenants that restrict our ability to dispose of assets, create liens, incur indebtedness, repurchase stock, pay dividends, make acquisitions and make investments. Further, the 2013 Credit Facility contains financial covenants that require the maintenance of minimum consolidated interest coverage and maximum consolidated leverage ratios. Specifically, we must maintain, as of the end of each fiscal quarter, an interest coverage ratio of (a) EBITDA (as defined in the 2013 Credit Facility) to (b) interest expense for the most recently ended period of four fiscal quarters of not less than 3.50 to 1.00. We must also maintain, at the end of each fiscal quarter, a consolidated leverage ratio of (x) consolidated funded debt to (y) consolidated EBITDA (as defined in the 2013 Credit Facility) as of the last day of any fiscal quarter of the Borrower as set forth in the table below:
	Fiscal Quarter Ending	Consolidated Leverage Ratio
	December 31, 2013 to December 31, 2014	3.50 to 1.00
	March 31, 2015 to December 31, 2015	3.25 to 1.00
	March 31, 2016 and thereafter	3.00 to 1.00
	We were in compliance with all restrictive covenants of the term loan agreements as of December 31, 2014.
	In the year ended December 31, 2014 and 2013, total interest expense was $11.1 million and $23.7 million, respectively. In December 2013, we recognized a $12.3 million charge to Interest expense and other, net for the write-off of deferred debt issuance costs upon the pay-off of the 2012 Credit Facility.
	The following table summarizes the future minimum principal payments on the 2013 Credit Facility outstanding as of December 31, 2014:
	Fiscal year	(in thousands)
	2015	$	15,000
	2016	30,000
	2017	30,000
	2018	435,000
	Thereafter	—
	Total	$	510,000

Common_Stock

Common Stock	12 Months Ended
	Dec. 31, 2014
Share-based Compensation [Abstract]
Common Stock	COMMON STOCK
	On November 10, 2013, our Board of Directors authorized and declared a dividend distribution of one right (a Right) for each outstanding share of common stock to stockholders of record at the close of business on November 21, 2013 (the Record Date). Each Right entitles the registered holder to purchase from us one one-thousandth of a share of Series A Participating Preferred Stock, par value $0.0001 per share (the Preferred Shares), at an exercise price of $75.00 per one one-thousandth of a Preferred Share, subject to adjustment (the Exercise Price). The complete terms of the Rights are set forth in a Preferred Shares Rights Agreement (the Rights Agreement), dated as of November 11, 2013 and as amended November 27, 2013, between Riverbed and Computershare Trust Company, N.A., as rights agent. Subject to certain exceptions specified in the Rights Agreement, the Rights will separate from the common stock and become exercisable following (i) the 10th business day (or such later date as may be determined by the Board of Directors) after the public announcement that a person or group of affiliated or associated persons (an Acquiring Person) has acquired beneficial ownership of 10% (or 20% in the case of certain institutional investors who report their holdings on Schedule 13G) or more of the common stock or (ii) the 10th business day (or such later date as may be determined by the Board of Directors) after a person or group announces a tender or exchange offer that would result in ownership by a person or group of 10% (or 20% in the case of certain institutional investors who report their holdings on Schedule 13G) or more of the common stock. Until such a time, the Rights are inseparable from our common stock. The Rights have a de minimus fair value. In November 2014, the expiration of the Rights Agreement was extended to November 11, 2015.
	Stock Plans
	In July 2002, our Board of Directors adopted the 2002 Stock Plan (the 2002 Plan). In April and May 2006, our Board of Directors approved the 2006 Equity Incentive Plan (the 2006 Plan), the 2006 Employee Stock Purchase Plan (the Purchase Plan), and the 2006 Director Option Plan, which became effective upon our Initial Public Offering. In September 2006, all shares of common stock available for grant under the 2002 Plan transferred to the 2006 Plan. In May 2014, our Board of Directors adopted the 2014 Equity Incentive Plan (the 2014 Plan), which replaced the 2006 Plan, the 2006 Director Plan, and the 2012 Stock Incentive Plan.
	The Plans provide for automatic replenishments as follows:
	•	2006 Employee Stock Purchase Plan — Through January 2013, the Purchase Plan increased on January 1 of each year by a number of shares equal to the lesser of (i) 1,500,000 shares or (ii) 1% of the shares of common stock outstanding at that time or (iii) the number of shares determined by the Board. Effective May 22, 2013, the stockholders approved a 10,000,000 share increase to the Purchase Plan and the annual evergreen provision was discontinued.
	In February 2009, our Board of Directors adopted the 2009 Inducement Equity Incentive Plan (the 2009 Plan). The objective of the 2009 Plan is to provide incentives to attract, retain, and motivate eligible persons whose potential contributions are important to promote our long-term success and the creation of stockholder value. The 2009 Plan is intended to comply with NASDAQ Rule 5635(c)(4), which governs granting certain awards as a material inducement to an individual entering into employment with us. The 2009 Plan may be used for new hire equity grants should the Board of Directors determine to do so in the future.
	Pursuant to our December 2012 acquisition of OPNET, we assumed the Riverbed 2012 Stock Incentive Plan (2012 Plan) (formerly named the OPNET Technologies, Inc. 2010 Stock Incentive Plan), including all outstanding shares of restricted stock, all outstanding restricted stock units, and all shares available for future issuance under the Riverbed 2012 Stock Incentive Plan, and all of such securities became issuable for shares of our common stock, subject to appropriate adjustments to the number of shares pursuant to the Merger Agreement. The Riverbed 2012 Stock Incentive Plan provides for the number of shares of common stock available for issuance under the 2012 Plan to automatically increase on the first trading day of each calendar year, beginning with the 2013 calendar year and continuing through the term of the 2012 Plan, by an amount equal to the lesser of (i) 1,631,762 shares of common stock, or (ii) an amount determined by the Board.
	Also pursuant to our December 2012 acquisition of OPNET, we assumed certain outstanding options to purchase common stock of OPNET granted under the OPNET Technologies, Inc. Amended and Restated 2000 Stock Incentive Plan, and such options became exercisable to purchase shares of our common stock, subject to appropriate adjustments to the number of shares and exercise price of each assumed option pursuant to the Merger Agreement.
	A summary of shares available for grant as of December 31, 2014 is as follows:
	(in thousands)	Year ended December 31,
		2014
	2014 Plan	11,902
	2009 Inducement equity incentive plan	787
	Purchase plan	8,493
	Total	21,182
	Stock-Based Compensation Expense
	The following table summarizes stock-based compensation expense for stock options, RSUs and the Purchase Plan recorded in our statement of operations:
	(in thousands)		Year ended December 31,
			2014				2013			2012
	Cost of product		$	1,461			$	1,212		$	942
	Cost of support and services		8,642				8,832			6,853
	Sales and marketing		36,113				40,991			35,668
	Research and development		28,677				25,183			28,645
	General and administrative		15,614				14,339			17,186
	Total stock-based compensation expense		$	90,507			$	90,557		$	89,294
	Share-Based Payments Valuation Assumptions
	The fair value of options granted and Purchase Plan shares granted was estimated at the date of grant using the following assumptions:
			Year ended December 31,
			2014		2013		2012
	Employee Stock Options
	Expected term in years		4.3 - 4.4		4.3 - 4.4		4.2 - 4.3
	Risk-free interest rate		1.3% - 1.4%		0.7% - 1.2%		0.6% - 0.7%
	Volatility		48% - 52%		53% - 63%		62% - 66%
			Year ended December 31,
			2014		2013		2012
	Purchase Plan
	Expected term in years		0.5 - 2.0		0.5 - 2.0		0.5 - 2.0
	Risk-free interest rate		0.05% - 0.50%		0.08% - 0.30%		0.14% - 0.29%
	Volatility		22% - 43%		40% - 64%		63% - 74%
	Stock Options
	Options issued under our stock option plans are generally for periods not to exceed 10 years and are issued with an exercise price equal to the market value of our common stock on the date of grant, as determined by the last sale price of such stock on the Nasdaq Global Select Market. Options typically vest either 25% of the shares one year after the options’ vesting commencement date and the remainder ratably on a monthly basis over the following three to four years. Options granted under the 2002 Plan prior to May 31, 2006 have a maximum term of ten years, and beginning May 31, 2006 have a maximum term of seven years. Options granted under the 2006 Plan have a maximum term of seven years. Options granted under the 2006 Director Option Plan prior to March 4, 2008 have a maximum term of ten years, and options granted beginning March 4, 2008 have a maximum term of seven years. Options granted under the 2009 Plan have a maximum term of seven years.
	As of December 31, 2014, total compensation cost related to stock options granted to employees and directors not yet recognized was $14.9 million, net of estimated forfeitures. This cost will be recognized on a straight-line basis over the remaining weighted-average service period of 2.0 years.
	The following table summarizes information about stock options activity under all stock option plans:
	(in thousands, except per share amounts)		Options			Weighted			Weighted Average		Aggregate
			Outstanding			Average			Remaining		Intrinsic Value
						Exercise			Contractual Term
						Price			(in years)
	Balance at December 31, 2013		11,951			$	16.84		3.67		$	48,405
	Granted		134			$	19.77
	Exercised		(3,767	)		$	11.55
	Forfeited or expired		(1,081	)		$	22.55
	Balance at December 31, 2014		7,237			$	18.79		3.29		$	32,783
	Exercisable		5,446			$	18.94		2.7		$	27,225
	Vested and expected to vest		6,999			$	18.8		3.19		$	32,067
	The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying stock option awards and the closing price of our common stock at December 31, 2014. During the years ended December 31, 2014, 2013 and 2012, the aggregate intrinsic value of stock option awards exercised was $31.2 million, $37.8 million, and $45.9 million, respectively, determined at the date of option exercise.
	The weighted average grant-date fair value of options granted for the years ended December 31, 2014, 2013 and 2012, was $7.53, $6.30, and $10.19 per share, respectively.
	Stock Purchase Plan
	Under the Purchase Plan, employees may purchase shares of common stock through payroll deductions at a price per share that is 85% of the lesser of the fair market value of our common stock as of the beginning of an applicable offering period or the applicable purchase date. Offering periods are generally 24 months with purchases generally every 6 months. Employees’ payroll deductions may not exceed 15% of their compensation. Employees may purchase up to 4,000 shares per purchase period provided that the value of the shares purchased in any calendar year does not exceed IRS limitations.
	As of December 31, 2014, there was $7.0 million of total compensation cost, net of estimated forfeitures, left to be recognized under our Purchase Plan, which will be recognized over the remaining Purchase Plan offering period, which is up to 22 months.
	The weighted average fair value of grants for the years ended December 31, 2014, 2013 and 2012, was $5.69, $5.85, and $8.67 per share, respectively.
	Restricted Stock Units
	RSUs, which include performance-based RSUs, are granted to our employees and eligible executives, under the 2006 Plan. We expense the cost of nonvested RSUs, which is determined to be the fair market value of the shares of our common stock at the date of grant, ratably over the service period.
	The number of performance-based RSUs that are earned is generally variable based upon meeting certain annual performance targets, and vesting occurs three years from the date of grant.
RSUs generally vest over a period of three to four years from the date of grant. Until vested, RSUs do not have the voting rights of common stock and the shares underlying the awards are not considered issued and outstanding.
As of December 31, 2014, total unrecognized compensation cost related to nonvested RSUs to employees and directors not yet recognized was $126.3 million, net of estimated forfeitures. This cost will be recognized over the remaining weighted-average service period of 2.6 years.
The following table summarizes information about RSU activity for the year ended as of December 31, 2014:
(in thousands, except per share amounts)		Number of Shares			Weighted
					Average Grant
					Date Fair Value
Balance at December 31, 2013		9,126			$	17.67
Granted		6,488			$	19.31
Vested		(3,151	)		$	18.96
Forfeited		(2,548	)		$	17.11
Balance at December 31, 2014		9,915			$	17.69
The weighted average grant-date fair value of RSUs granted in the years ended December 31, 2014, 2013 and 2012 were $19.31, $16.94, and $20.85, respectively.
Share Repurchase Program
On August 19, 2011, our Board of Directors authorized a Share Repurchase Program (the Program), which authorized us to repurchase up to $150.0 million of our outstanding common stock. On May 17, 2012, our Board of Directors approved a $150.0 million increase to the Program. On August 19, 2013, our Board announced a $200.0 million increase to the Program. On March 4, 2014, the Board announced a $250.0 million increase, for a total authorized repurchase amount under the program of $750.0 million. The Program does not require us to purchase a minimum number of shares, and may be suspended, modified or discontinued at any time without prior notice. The timing and amounts of these purchases are based on market conditions and other factors, including price, regulatory requirements and capital availability. The share repurchases were financed by available cash balances and cash from operations.
For the year ended December 31, 2014, we repurchased 10.2 million shares of common stock under the Program on the open market for an aggregate purchase price of $195.6 million, or a weighted average of $19.24 per share. For the year ended December 31, 2013, we repurchased 12.4 million shares of common stock under the Program on the open market for an aggregate purchase price of $200.1 million, or a weighted average of $16.11 per share. For the year ended December 31, 2012, we repurchased 7.4 million shares of common stock under the Program on the open market for an aggregate purchase price of $127.1 million, or a weighted average of $17.24 per share. The amount remaining available under the program was $192.2 million as of December 31, 2014.
The timing and amounts of these purchases were based on market conditions and other factors including price, regulatory requirements and capital availability. The share repurchases were financed by available cash balances and cash from operations.

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES
	A geographical breakdown of income (loss) before provision for (benefit from) income taxes is shown in the following table:
		Year ended December 31,
	(in thousands)	2014			2013			2012
	Domestic	$	44,359		$	(46,884	)	$	50,095
	Foreign	50,511			20,319			43,938
	Total	$	94,870		$	(26,565	)	$	94,033
	The provision for (benefit from) income tax expense consists of the following:
		Year ended December 31,
	(in thousands)	2014			2013			2012
	Current:
	Federal	$	37,482		$	25,396		$	24,105
	State	6,163			2,971			2,629
	Foreign	9,066			6,423			7,267
	Total current	$	52,711		$	34,790		$	34,001
	Deferred:
	Federal	$	(23,719	)	$	(35,731	)	$	6,483
	State	(4,752		)	(12,920		)	917
	Foreign	(638		)	(286		)	(1,965		)
	Total deferred	$	(29,109	)	$	(48,937	)	$	5,435
	Total provision for (benefit from) income taxes	$	23,602		$	(14,147	)	$	39,436
	Our effective tax rate was 24.9%, 53.3%, and 41.9%, for the years ended December 31, 2014, 2013 and 2012, respectively.
	The difference between the provision for (benefit from) income taxes and the amount computed by applying the federal statutory income tax rate to income before taxes is as follows:
		Year ended December 31,
	(in thousands)	2014			2013			2012
	Expected provision at federal statutory rate	$	33,204		$	(9,298	)	$	32,910
	State taxes, net of federal benefit	788			(6,425		)	2,172
	Stock-based compensation expense	10,212			12,606			9,088
	Intercompany transfers of intellectual property	(4,020		)	3,552			6,614
	Acquisition related expenses	—			—			2,230
	Research and development tax credits	(5,692		)	(8,392		)	(964		)
	Foreign rate differential	(14,012		)	(6,172		)	(11,920		)
	Domestic production activities deduction	(3,221		)	(2,227		)	(299		)
	Meals and entertainment	523			494			400
	Change in uncertain tax positions, including interest	(489		)	1,167			122
	Disposition of non-deductible goodwill related to sale of product line	6,779			—			—
	Other (net)	(470		)	548			(917		)
	Total	$	23,602		$	(14,147	)	$	39,436
	The components of our deferred tax assets and liabilities consisted of the following:
		As of December 31,
	(in thousands)	2014			2013
	Deferred tax liabilities:
	Depreciation and amortization	$	(8,194	)	$	(4,604	)
	Intangible Assets	(81,637		)	(101,925		)
	Total deferred tax liabilities	$	(89,831	)	$	(106,529	)
	Deferred tax assets:
	Deferred compensation	$	26,702		$	29,863
	Credit carryforwards	20,161			16,763
	Deferred revenue	5,588			915
	Net operating losses	8,631			9,967
	Other accrued liabilities and reserves	31,637			20,809
	State taxes	1,393			3,128
	Total deferred tax assets	$	94,112		$	81,445
	Valuation allowance	$	(19,411	)	$	(16,168	)
	Total net deferred tax liabilities	$	(15,130	)	$	(41,252	)
	The components of our deferred tax assets and liabilities consisted of the following:
	(in thousands)	As of December 31,
		2014			2013
	Current deferred tax assets	$	31,802		$	7,222
	Non-current deferred tax assets	1			74
	Non-current deferred tax liabilities	(46,933		)	(48,548		)
	Net deferred tax liabilities	$	(15,130	)	$	(41,252	)
	We have not provided U.S. taxes for our foreign earnings, which are intended to be indefinitely reinvested outside the U.S. As of December 31, 2014, we had cumulative undistributed earnings of foreign subsidiaries of approximately $159.4 million, which are intended to be reinvested and for which no U.S. income or foreign withholding taxes have been recorded. Determination of the amount of unrecognized deferred tax liability with respect to such earnings is not practicable. The additional taxes on the earnings of foreign subsidiaries, if remitted, would be partially offset by U.S. tax credits for foreign taxes already paid.
	We are subject to a reduced income tax rate in Singapore as a result of certain employment and spending commitments. The reduced tax rate is effective through 2020. For the years ended December 31, 2014, 2013 and 2012, we realized a tax benefit of $5.0 million ($0.03 per diluted share), $1.7 million ($0.01 per diluted share), and $3.8 million ($0.02 per diluted share), respectively.
During the year ended December 31, 2013, the American Taxpayer Relief Act of 2012 reinstated the U.S. federal R&D tax credit through December 31, 2013, retroactive to January 1, 2012. As a result, the tax provision for the year ended December 31, 2013 includes a tax benefit of $4.4 million related to the federal R&D tax credit for the year ended December 31, 2012.
During 2013, we completed the integration of the OPNET business into our existing tax structure and intercompany relationships to more closely align with the international nature of our business activities. Our corporate restructuring activities may cause volatility to our overall effective tax rate in the short term but is expected to reduce our overall effective tax rate over the long term.
During the year ended December 31, 2013, we changed the tax status of certain OPNET subsidiaries to entities that are disregarded for federal and state income tax purposes. As a result of the change in tax status, we recorded a state income tax benefit of $4.4 million, net of federal benefit, to record the revaluation of OPNET’s deferred tax assets and liabilities resulting from the change.
Based on our forecasted future income allocated to California, it is more likely than not the California income tax credit carryforwards will not be utilized in the foreseeable future. Accordingly, we have established a full valuation allowance against the tax credits. The amount of the valuation allowance against the California credits was $12.6 million and $10.5 million, net of federal benefit, for the years ended December 31, 2014 and 2013, respectively.
As of December 31, 2014, we had net operating loss carryforwards for federal, state and foreign income tax purposes of $22.5 million, $4.9 million and $1.4 million, respectively. The utilization of the federal loss and a majority of state loss carryforwards are subject to limitation under Section 382 of the Internal Revenue Code. As of December 31, 2014, we also had federal and state R&D tax credit carryforwards of approximately $0.5 million and $32.9 million, respectively. If not utilized, the federal and state net operating loss carryforwards will expire between 2024 and 2027. The federal R&D tax credit carryforwards will expire between 2026 and 2030. The state R&D tax credit carryforwards and the foreign net operating loss carryforwards do not expire.
During the year ended December 31, 2014, we reduced our current federal, foreign and state taxes payable by $2.3 million for the excess tax benefits from stock option exercises and other employee stock programs, offsetting additional paid-in capital. In addition, we have unrecorded excess tax benefits from stock option exercises and other employee stock programs of approximately $5.9 million as of December 31, 2014. These amounts will be credited to additional paid-in-capital when such amounts reduce cash taxes payable.
Uncertain Income Tax Positions
A reconciliation of the beginning and ending amount of the consolidated liability for unrecognized income tax benefits during the year is as follows:
	Year ended December 31,
(in thousands)	2014			2013			2012
Beginning balance	$	53,115		$	30,690		$	26,995
Additions for tax positions of prior years	175			2,485			930
Additions for tax positions related to current year	6,699			21,306			3,810
Reductions for tax positions of prior year	(8,422		)	(1,351		)	(979		)
Settlements	—			(15		)	(66		)
Ending balance	$	51,567		$	53,115		$	30,690
As of December 31, 2014, 2013 and 2012, the unrecognized tax benefits of $51.6 million, $53.1 million and $30.7 million, respectively, included tax benefits that, if recognized, would reduce our effective tax rate by $39.8 million, $43.4 million and $21.9 million, respectively. As of December 31, 2014, 2013 and 2012, the ending balance of accrued interest and penalties associated with uncertain tax positions is $2.2 million, $1.8 million and $0.5 million, respectively. For the years ended December 31, 2014, 2013 and 2012, we accrued $0.7 million, $1.1 million, and $0.2 million of interest and penalties. Over the next 12 months, our unrecognized tax benefits could be reduced by up to $14.5 million.
As of December 31, 2014, we had $53.8 million of unrecognized tax benefits (including $2.2 million related to interest and penalties) related to our uncertain tax positions. Of this amount, $45.7 million is included in Other long-term liabilities. The remaining $8.1 million is reported as a reduction of deferred tax assets.
We are subject to income tax in the U.S. as well as numerous state and foreign jurisdictions. We are no longer subject to federal examinations for years before 2009. With the exception of several states, we are no longer subject to state and local income tax examinations for years before 2011, although carryforward attributes that were generated prior to 2011 may still be adjusted upon examination by the California Franchise Tax Board if the attributes either have been or will be used in a future period. In addition, we file tax returns in multiple foreign taxing jurisdictions. In our most significant foreign jurisdictions, the UK and Singapore, the open tax years range from 2011 to 2013.

Segment_Information

Segment Information	12 Months Ended
	Dec. 31, 2014
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Segment Information	SEGMENT AND GEOGRAPHIC INFORMATION
	Operating segments are defined as components of an enterprise about which separate financial information is available that is evaluated regularly by the chief operating decision maker, or decision making group, in deciding how to allocate resources and in assessing performance. Our chief operating decision maker is our Chief Executive Officer. While our Chief Executive Officer evaluates the financial information for certain of our product lines, the information for all product lines is aggregated for analysis on a consolidated level as the primary basis for the allocation of resources and assessment of financial results. Accordingly, the consolidated business is considered to be one operating segment.
	Revenue by Product Line
	We have two product lines: Application Acceleration and Performance Management. Application Acceleration includes our wide area network (WAN) optimization products, including SteelHead and SteelFusion (formerly Granite), our SteelApp (formerly Stingray; In February 2015, Riverbed and Brocade signed a definitive agreement pursuant to which Brocade will, at closing, purchase the SteelApp product line) virtual application delivery controllers (ADCs), and our SteelStore (formerly Whitewater, sold to NetApp in October 2014) cloud storage delivery products. Performance Management includes our SteelCentral performance management and control suite. The Performance Management product line combines our former Cascade products and the products acquired from OPNET.
	The following table presents revenue by product line:
		Year ended December 31,
	(in thousands)	2014		2013		2012
	Application Acceleration	$	831,765	$	807,469	$	767,037
	Performance Management	257,443		233,564		69,823
	Total revenue	$	1,089,208	$	1,041,033	$	836,860
	Revenue by geography is based on the billing address of the customer. The following table sets forth revenue by geographic area.
	Revenue by Geography
		Year ended December 31,
	(in thousands)	2014		2013		2012
	Americas
	United States	$	621,209	$	611,469	$	463,534
	Other Americas	33,893		38,351		31,373
	Total Americas	655,102		649,820		494,907
	Europe, Middle East and Africa
	United Kingdom	147,069		118,022		124,458
	Other Europe, Middle East and Africa	145,645		140,335		101,194
	Total Europe, Middle East and Africa	292,714		258,357		225,652
	Asia Pacific	141,392		132,856		116,301
	Total revenue	$	1,089,208	$	1,041,033	$	836,860

Employee_Benefit_Plan

Employee Benefit Plan	12 Months Ended
	Dec. 31, 2014
General Discussion of Pension and Other Postretirement Benefits [Abstract]
Employee Benefit Plan	EMPLOYEE BENEFIT PLAN
	We have a 401(k) plan covering all eligible employees. At our discretion, we may match a portion of the employees’ eligible contributions. Contributions to the plan during the years ended December 31, 2014, 2013 and 2012, were $8.1 million, $7.8 million and $5.1 million, respectively.

Legal_Matters

Legal Matters	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Legal Matters	LEGAL MATTERS
	On June 1, 2011, we served Silver Peak Systems, Inc. with a lawsuit, filed in the United States District Court for the District of Delaware, alleging infringement of certain patents. The lawsuit seeks unspecified damages and injunctive relief. On July 22, 2011, Silver Peak Systems denied the allegations and requested declaratory judgments of invalidity and non-infringement. On December 21, 2011, we amended our lawsuit against Silver Peak Systems to allege infringement of an additional patent. Our lawsuit against Silver Peak Systems currently alleges infringement of three patents. Trial of our claims against Silver Peak Systems in this matter is currently stayed pending a separate U.S. Patent and Trademark Office proceeding.
	On August 17, 2011, Silver Peak Systems amended its counterclaims against us, alleging infringement by Riverbed of three U.S. patents: 7,630,295, titled “Network Device Continuity”; 7,945,736, titled “Dynamic Load Management of Network Memory”; and 7,948,921, titled “Automatic Network Optimization.” Silver Peak subsequently dropped its claims with respect to U.S. patent 7,630,295. The trial on the remaining two patents commenced on March 24, 2014. On April 1, 2014, the jury rendered a verdict of infringement on U.S. patents 7,948,921 and 7,945,736 based on certain features offered on Riverbed SteelHead products. We disagree with the verdict, and we intend to appeal to the Federal Circuit. There has been no trial or discovery on damages, and we expect that such a trial and discovery would be scheduled only if we lose on appeal to the Federal Circuit.
	At this time we are unable to estimate any range of reasonably possible loss relating to these actions.
	On June 28, 2013, we served Silver Peak Systems with an additional lawsuit, filed in the United States District Court for the Northern District of California, alleging infringement of two patents that are not covered by the lawsuit in Delaware. The California lawsuit seeks unspecified damages and injunctive relief. On July 22, 2013, Silver Peak Systems denied the allegations and requested declaratory judgments of invalidity and non-infringement. On August 12, 2013, Silver Peak Systems amended its counterclaims against us, alleging infringement by Riverbed of U.S. patent 8,392,684, titled “Data Encryption in a Network Memory Architecture for Providing Data Based on Local Accessibility”. On August 26, 2013 we denied Silver Peak Systems’ allegations and requested declaratory judgments of invalidity and non-infringement. On July 29, 2014, the Court lifted the stay that was in place on our action against Silver Peak, though no trial date has been set. The action against us is currently stayed pending a separate U.S. Patent and Trademark Office proceeding. At this time we are unable to estimate any range of reasonably possible loss relating to these actions. We believe that we have meritorious defenses to the counterclaims against us, and we intend to vigorously contest these counterclaims.
	In connection with our July 2011 acquisition of the outstanding securities of Zeus Technology Limited (Zeus), the share purchase agreement provided for certain additional potential payments (acquisition-related contingent consideration) totaling up to $27.0 million in cash, based on achievement of certain bookings targets related to Zeus products for the period from July 20, 2011 through July 31, 2012 (the Zeus Earn-Out period). The share purchase agreement also provided for a potential $3.0 million payment as an incentive bonus to former employees of Zeus, based on achievement of certain bookings targets related to Zeus products for the Zeus Earn-Out period.
	In October 2012 we served the representative of the Zeus shareholders, as lead defendant and proposed defendant class representative for all other similarly situated former shareholders of Zeus, with a lawsuit, filed in the Superior Court of the State of California, for declaratory relief.  The lawsuit seeks declaratory judgment that, among other things, (a) Riverbed is not in breach of the share purchase agreement, and (b) Riverbed does not owe any acquisition-related contingent consideration under the share purchase agreement because the necessary conditions precedent to the payment of acquisition-related contingent consideration did not occur. In November 2012, the representative of the Zeus shareholders filed a cross-complaint against Riverbed and Riverbed Technology Limited in the Superior Court of the State of California. The cross-complaint claims breach of contract and breach of the covenant of good faith and fair dealing, and seeks declaratory judgment that Riverbed has breached the share purchase agreement and that the entire $27.0 million in contingent consideration is payable to Zeus shareholders. Discovery is ongoing, and the Court has approved a class treatment of the former shareholders, though several have declined to participate. The trial is currently scheduled for August 31, 2015, though may be rescheduled to an earlier date pending the Court’s availability. We believe that the contention of the representative of the Zeus shareholders, and the Court-appointed class representatives for shareholders, is without merit and intend to vigorously defend our determination.
	In November 2012 we received a grand jury subpoena issued by the United States District Court for the Eastern District of Virginia. The subpoena requested documents related to certain federal government contracting matters, including a $19 million transaction involving the sale of our products and services by a Riverbed reseller to an agency of the federal government in 2009. In January 2014 we received a notice that the Civil Division of the United States Attorney’s Office for the Eastern District of Virginia has opened a civil investigation into the same matters.
	In connection with the merger agreement and the transactions contemplated thereby, ten purported class action lawsuits have been filed. Seven complaints, captioned Gary Merryman, Individually and On Behalf of All Others Similarly Situated v. Riverbed Technology, Inc., et al., filed on December 19, 2014 and amended on January 21, 2015, Kamesh Bathla, On Behalf of Himself and All Others Similarly Situated v. Riverbed Technology, Inc. et al., filed on December 22, 2014 and amended on January 14, 2015, Domenico Carlucci, Individually and On Behalf of All Others, Similarly Situated v. Riverbed Technology, Inc. et al., filed on December 23, 2014 and amended on January 15, 2015, First Financial Trust, Individually and On Behalf of All Others Similarly Situated v. Riverbed Technology, Inc. et al., filed on December 23, 2014, Gerard Byrne, Individually and On Behalf of All Others Similarly Situated v. Boustridge et al., filed on December 24, 2014, Richard Krol, On Behalf of Himself and All Others Similarly Situated v. Riverbed Technology, Inc. et al., filed on January 8, 2015 and amended on January 15, 2015, and David Jessen v. Riverbed Technology, Inc. et al., filed on January 15, 2015, were filed in the Court of Chancery of the State of Delaware. On January 30 and February 2, 2015, the Delaware actions were consolidated as In Re Riverbed Technology Inc. Shareholder Litigation. Two complaints, captioned Ken Steiger, On Behalf of Himself and All Others Similarly Situated v. Riverbed Technology, Inc., et al., filed on January 16, 2015, and Louis Benson, On Behalf of Himself and All Others Similarly Situated v. Riverbed Technology, Inc., et al., filed January 20, 2015, were filed in the San Francisco Superior Court, in the State of California. One complaint captioned Seth Olson, Individually and On Behalf of All Others Similarly Situated v. Riverbed Technology, Inc., et al., filed February 5, 2015, was filed in the United States District Court for the Northern District of California, San Francisco Division. In general, the complaints assert that, among other things, the members of the Board of Directors breached their fiduciary duties to stockholders by initiating a process that undervalues Riverbed, by agreeing to a transaction that does not adequately reflect Riverbed’s true value, and/or by failing to disclose material information relating thereto, and that Riverbed, Newco, Merger Sub, Thoma Bravo, Ontario Teachers’ Pension Plan Board, and/or Elliott aided and abetted the Board of Directors’ breaches of fiduciary duties. The federal complaint further asserts violations of federal securities laws related to the dissemination of the purportedly false and materially misleading proxy and seeks a declaration that certain provisions in the Company’s amended and restated bylaws concerning forum selection and fee shifting are invalid. The complaints generally seek to enjoin the merger or, alternatively, seek rescission of the merger in the event the defendants are able to consummate it. We intend to vigorously contest these claims.
	From time to time, we are subject to various legal proceedings, claims and litigation arising in the ordinary course of business. We do not believe we are party to any currently pending legal proceedings the outcome of which would have a material adverse effect on our financial position, results of operations, or cash flows. There can be no assurance that existing or future legal proceedings arising in the ordinary course of business or otherwise will not have a material adverse effect on our financial position, results of operations, or cash flows.

Related_Parties

Related Parties	12 Months Ended
	Dec. 31, 2014
Related Party Transactions [Abstract]
Related Parties	RELATED PARTIES
	There were no significant related party transactions occurred in the years ended December 31, 2014, 2013 and 2012.

Subsequent_Event_Notes

Subsequent Event (Notes)	12 Months Ended
	Dec. 31, 2014
Subsequent Event [Abstract]
Subsequent Events [Text Block]
	21	SUBSEQUENT EVENT
	On February 4, 2015, we entered into a definitive agreement with Brocade for the sale of our SteelApp product line. Revenues from the sale of the SteelApp products and services to be divested were $31.1 million, $35.8 million, and $28.4 million in 2014, 2013, and 2012, respectively.
	As of December 31, 2014 we have classified the SteelApp related assets and liabilities as Assets and Liabilities held for sale in our consolidated balance sheet.

Valuation_and_Qualifying_Accou

Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2014
Valuation and Qualifying Accounts [Abstract]
Schedule of Valuation and Qualifying Accounts Disclosure [Text Block]	Valuation and Qualifying Accounts
		Year ended December 31,
	(in thousands)	2014			2013			2012
	Trade Receivables Allowance
	Beginning balance	$	1,996		$	2,064		$	1,586
	Additions charged to operations	24			919			825
	Write-offs	(476		)	(987		)	(347		)
	Ending balance	$	1,544		$	1,996		$	2,064

Organization_And_Significant_A1

Organization And Significant Accounting Policies (Policy)	12 Months Ended
	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	Organization
	Riverbed Technology, Inc. was founded on May 23, 2002 and is a leader in application performance infrastructure. Riverbed gives enterprises the visibility to deliver, control, and optimize IT resources across the hybrid enterprise through the Riverbed Application Performance Platform, a set of integrated solutions that give companies the flexibility to host applications and data in the locations that best serve the business while ensuring the flawless delivery of those applications to better leverage global resources, radically reduce the cost of running their business, and maximize employee productivity. Riverbed’s solutions dramatically improve application performance, reduce IT costs, and substantially increase business agility.
Basis of Presentation	Basis of Financial Statements
	The consolidated financial statements include our accounts and the accounts of our wholly owned subsidiaries. Intercompany transactions and balances have been eliminated.
Use of Estimates	Use of Estimates
	Our consolidated financial statements are prepared in United States (U.S.) generally accepted accounting principles (GAAP). These accounting principles require us to make certain estimates and judgments that can affect the reported amounts of assets and liabilities as of the date of the consolidated financial statements, as well as the reported amounts of revenue and expenses during the periods presented. Significant estimates and assumptions made by management include the determination of the fair value of stock awards issued, inventory valuation, the accounting for income taxes, including the determination of the valuation allowance related to our deferred tax asset balances, liabilities for uncertain tax positions, goodwill and other intangible assets, and the accounting for business combinations. We believe that the estimates and judgments upon which we rely are reasonable based upon information available to us at the time that these estimates and judgments were made. To the extent there are material differences between these estimates and actual results, our consolidated financial statements will be affected.
Cash and Cash Equivalents	Cash and Cash Equivalents
	We consider all highly liquid investments purchased with original maturities at the date of purchase of three months or less to be cash equivalents. Cash and cash equivalents are stated at cost, which approximates fair value.
Investments	Investments
	We determine the appropriate classification of short and long-term investments at the time of purchase and re-evaluate such determination at each balance sheet date. The fair value of our investments is determined as the exit price in the principal market in which we would transact. Securities, which are classified as available for sale at December 31, 2014, 2013 and 2012, are carried at fair value, with the unrealized gains and losses, net of tax, reported as a separate component of stockholders’ equity. Unrealized gains and losses to date have not been material. Realized gains and losses and declines in value judged by us to be other-than-temporary on securities available for sale are included as a component of Interest expense and other, net. The cost of securities sold is based on the specific-identification method. Interest on securities classified as available for sale is included as a component of Interest expense and other, net.
Inventory Valuation	Inventory Valuation
	Inventory consists of hardware and related component parts and is stated at the lower of cost (on a first-in, first-out basis) or market. A portion of our inventory relates to evaluation units located at customer locations, as some of our customers test our equipment prior to purchasing. Inventory that is obsolete or in excess of our forecasted demand is written down to its estimated realizable value based on historical usage, expected demand, and with respect to evaluation units, the historical conversion rate, the age of the units, and the estimated loss of utility. Inherent in our estimates of market value in determining inventory valuation are estimates related to economic trends, future demand for our products, the timing of new product introductions and technological obsolescence of our products. Inventory write-downs, including estimated loss of utility on evaluation units, are recognized as cost of product and amounted to approximately $8.0 million, $11.2 million and $6.7 million for the years ended December 31, 2014, 2013 and 2012, respectively.
Service Inventory	Service Inventory
	We hold service inventory that is used to repair or replace defective hardware reported by our customers who purchase support services. We classify service inventory as Prepaid expenses and other current assets. At December 31, 2014 and 2013 our service inventory balance was $21.1 million and $20.8 million, respectively.
Internal-Use Software Development Costs	Internal-Use Software Development Costs
	We capitalize qualifying costs for computer software developed for or obtained for internal-use, which are incurred during the application development stage, and amortize them over the software’s estimated useful life, which is generally two to five years.
	We capitalized $9.9 million, $7.7 million and $6.9 million in internal use software during the years ended December 31, 2014, 2013 and 2012, respectively. Amortization expense related to these assets totaled $8.2 million, $6.7 million and $4.8 million during the years ended December 31, 2014, 2013 and 2012, respectively. Software development costs required to be capitalized for software sold, leased, or otherwise marketed have not been
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets
	We review long-lived assets and identifiable intangible assets, excluding goodwill, for impairment whenever events or changes in circumstances indicate that the carrying amount of these assets may not be recoverable. We assess these assets for impairment based on estimated undiscounted future cash flows from these assets. If the carrying value of the assets exceeds the estimated future undiscounted cash flows, a loss is recorded for the excess of the asset’s carrying value over the fair value. To date we have not recognized any impairment loss for long-lived assets.
Goodwill, Intangible Assets And Impairment Assessments	Goodwill, Intangible Assets and Impairment Assessments
	Goodwill represents the excess of the purchase price of an acquired business over the fair value of the underlying net tangible and intangible assets. Goodwill is tested for impairment at least annually (more frequently if certain indicators are present). In the event that we determine that the fair value of a reporting unit is less than the reporting unit’s carrying value, we will incur an impairment charge for the amount of the difference during the quarter in which the determination is made.
	Intangible assets that are not considered to have an indefinite life are amortized over their useful lives. On a periodic basis, we evaluate the estimated remaining useful life of purchased intangible assets and whether events or changes in circumstances warrant a revision to the remaining period of amortization. The carrying amounts of these assets are periodically reviewed for impairment whenever events or changes in circumstances indicate that the carrying value of these assets may not be recoverable. Recoverability of these assets is measured by comparison of the carrying amount of each asset to the future undiscounted cash flows the asset is expected to generate.
	In the event that we determine that the fair value of an intangible asset is less than the carrying value, we will incur an impairment charge for the amount of the difference during the quarter in which the determination is made. We did not recognize any material goodwill or intangible asset impairment charges in the years ended December 31, 2014, 2013 or 2012.
Revenue Recognition	Revenue Recognition
	We recognize revenue when all of the following have occurred: (1) we have entered into a legally binding arrangement with a customer; (2) delivery has occurred; (3) customer payment is deemed fixed or determinable and free of contingencies and significant uncertainties; and (4) collection is reasonably assured.
	The majority of our product revenue includes hardware appliances containing software components that function together to provide the essential functionality of the product. Therefore, our hardware appliances are considered non-software deliverables. Most non-software products and services qualify as separate units of accounting because they have value to the customer on a standalone basis and our revenue arrangements generally do not include a general right of return relative to delivered products. We account for non-software arrangements with multiple deliverables, which generally include support services sold with each of our hardware appliances, using the relative selling price method under the revenue recognition guidance for multiple deliverable arrangements.
	Our product revenue also includes revenue from the sale of stand-alone software products. Stand-alone software may operate on our hardware appliance, but is not considered essential to the functionality of the hardware. Stand-alone software products generally include a perpetual license to our software. Stand-alone software sales are subject to the industry specific software revenue recognition guidance.
	Certain arrangements with multiple deliverables may have stand-alone software deliverables that are subject to the software revenue recognition guidance along with non-software deliverables. The revenue for these multiple deliverable arrangements is allocated to the stand-alone software deliverables as a group and the non-software deliverables based on the relative selling prices of all of the deliverables in the arrangement.
	The amount of product and services revenue recognized for arrangements with multiple deliverables is impacted by their relative selling prices. We apply the selling price hierarchy using vendor specific objective evidence (VSOE) when available, third-party evidence of selling price (TPE) if VSOE does not exist, and estimated selling price (ESP) if neither VSOE nor TPE is available.
	VSOE of fair value for elements of an arrangement is based upon the normal pricing and discounting practices for a deliverable when sold separately, and VSOE for support services is measured by the renewal rate offered to the customer. In determining VSOE, we require that a substantial majority of the selling prices fall within a reasonably narrow pricing range, generally evidenced by a substantial majority of such historical stand-alone transactions falling within a reasonably narrow range of the median rates. In addition, we consider major service groups, geographies, customer classifications, and other variables in determining VSOE.
	We are typically not able to determine TPE for our products or services. TPE is determined based on competitor prices for similar deliverables when sold separately. Generally, our go-to-market strategy differs from that of our peers and our offerings contain a significant level of differentiation such that the comparable pricing of products with similar functionality cannot be obtained. Furthermore, we are unable to reliably determine what similar competitor products’ selling prices are on a stand-alone basis.
	When we are unable to establish the estimated stand-alone value of our non-software deliverables using VSOE or TPE, we use ESP in our allocation of arrangement consideration. The objective of ESP is to determine the price at which we would transact a sale if the product or service were sold on a stand-alone basis. We determine ESP for a product or service by considering multiple factors including, but not limited to, cost of products, gross margin objectives, pricing practices, geographies, customer classes and distribution channels.
	For stand-alone software sales, we recognize revenue based on software revenue recognition guidance. Under the software revenue recognition guidance, we use the residual method to recognize revenue when an agreement includes one or more elements to be delivered at a future date and VSOE of the fair value of all undelivered elements exists. In the majority of our contracts, the only element that remains undelivered at the time of delivery of the product is support services. Under the residual method, the fair value of the undelivered stand-alone software, which is typically support services, is deferred and the remaining portion of the contract fee is recognized as product revenue. If evidence of the fair value of one or more undelivered stand-alone software elements does not exist, all revenue is generally deferred and recognized when delivery of those elements occurs or when fair value can be established. When the undelivered stand-alone element for which we do not have VSOE of fair value is support, revenue for the entire arrangement is bundled and recognized ratably over the support period.
	For our non-software deliverables, we allocate the arrangement consideration based on the relative selling price of the deliverables. For our hardware appliances we use the ESP of the deliverable. For our support and services, we generally use VSOE as our relative selling price. When we are unable to establish VSOE for our support and services, we use ESP in our allocation of arrangement consideration. We regularly review VSOE and ESP. As our go-to-market strategies evolve, we may modify our pricing practices in the future, which could result in changes in selling prices, including both VSOE and ESP.
	For sales to direct end-users and channel partners, including value-added resellers, value-added distributors, service providers, and systems integrators, we recognize product revenue upon delivery, assuming all other revenue recognition criteria are met. For our hardware appliances, delivery occurs upon transfer of title and risk of loss, which is generally upon shipment. It is our practice to identify an end-user prior to shipment to a channel partner. For end-users and channel partners, we generally have no significant obligations for future performance such as rights of return or pricing credits. Shipping charges billed to customers are included in product revenue and the related shipping costs are included in cost of product revenue.
	Support and services consist of support services, professional services, and training. Support services include repair and replacement of defective hardware appliances, software updates and access to technical support personnel. Software updates provide customers with rights to unspecified software product upgrades and to maintenance releases and patches released during the term of the support period on a when-and-if-available basis. Open-enrollment training services which are delivered on a when-and-if-available basis may be bundled with support services. Revenue for support services is recognized on a straight-line basis over the service contract term, which is typically one to three years. Professional services are recognized upon delivery or completion of performance. Professional service arrangements are typically short term in nature and are largely completed within 90 days from the start of service. Training services are recognized upon delivery of the training.
	Our fees are typically considered to be fixed or determinable at the inception of an arrangement, generally based on specific products and quantities to be delivered. Substantially all of our contracts do not include rights of return or acceptance provisions. To the extent that our agreements contain such terms, we recognize revenue once the acceptance provisions or right of return lapses. Payment terms to customers generally range from net 30 to 90 days. In the event payment terms are provided that significantly differ from our standard business practices, the fees may be deemed to not be fixed or determinable and revenue is recognized when the payments become due, provided the remaining criteria for revenue recognition have been met.
	We assess the ability to collect from our customers based on a number of factors, including credit worthiness of the customer and past transaction history of the customer. If the customer is not deemed credit worthy, we defer revenue from the arrangement until payment is received and all other revenue recognition criteria have been met.
Stock-Based Compensation	Stock-Based Compensation
	Stock-based awards granted include restricted stock units (RSUs), stock purchased under our Employee Stock Purchase Plan (the Purchase Plan) and stock options. Stock-based compensation expense is measured at the grant date, based on the fair value of the awards, and is recognized as expense over the requisite service period only for those equity awards expected to vest.
	The fair value of the RSUs is determined based on the stock price on the date of grant. The fair value of the RSUs is amortized on a straight-line basis over the requisite service period of the awards, which is generally three to four years. We estimated the fair value of stock purchased under our Purchase Plan and stock options using the Black-Scholes model. This model utilizes the estimated fair value of common stock and requires that, at the date of grant, we use the expected term of the grant, the expected volatility of the price of our common stock, risk-free interest rates and expected dividend yield of our common stock. The fair value is amortized on a straight-line basis over the requisite service periods of the awards, which is generally three to four years for stock options, and six months to two years for stock purchased under our Purchase Plan.
	The expected term represents the period that stock options are expected to be outstanding. We estimated the expected term based on historical exercise patterns and post vesting termination behavior. We estimated the expected volatility of stock options using a blended historical and implied volatility data. The computation of expected volatility for the Purchase Plan is based on our historical volatility.
Business Combinations	Business Combinations
	In our business combinations, we are required to recognize all the assets acquired, liabilities assumed, contractual contingencies, and contingent consideration at their fair value on the acquisition date. Further, acquisition-related costs are recognized separately from the acquisition and expensed as incurred; restructuring costs are generally expensed in periods subsequent to the acquisition date; changes in the estimated fair value of contingent consideration after the initial measurement on the acquisition date are recognized in earnings in the period of the change in estimate; and changes in accounting for deferred tax asset valuation allowances and acquired income tax uncertainties after the measurement period are recognized as a component of provision for (benefit from) income taxes. In addition, the fair value of in-process research and development (R&D) is recorded as an indefinite-lived intangible asset until the underlying project is completed, at which time the intangible asset is amortized over its estimated useful life, or abandoned, at which time the intangible asset is expensed.
	Accounting for business combinations requires management to make significant estimates and assumptions, including the acquisition date fair value of intangible assets, estimated contingent consideration payments and pre-acquisition contingencies.
	Although we believe the assumptions and estimates we have made have been reasonable and appropriate, they are based in part on historical experience and information obtained from management of the acquired company and are inherently uncertain. Examples of critical estimates in accounting for acquisitions include but are not limited to:
	•	the estimated fair value of the acquisition-related contingent consideration, which is performed using a probability-weighted discounted cash flow model based upon the forecasted achievement of post-acquisition bookings targets;
	•	the future expected cost to develop the in-process R&D into commercially viable products and the estimated cash flows from the products when completed;
	•	the future expected cash flows from product sales, support agreements, consulting contracts, other customer contracts and acquired developed technologies and patents; and
	•	the discount rates.
	Unanticipated events and circumstances may occur which may affect the accuracy or validity of such assumptions, estimates or actual results.
Accounting for Income Taxes	Accounting for Income Taxes
	We use the asset and liability method of accounting for income taxes. Under this method, income tax expenses or benefits are recognized for the amount of taxes payable or refundable for the current year and for deferred tax liabilities and assets for the expected tax consequences of temporary differences between the tax bases of assets and liabilities for financial reporting purposes and amounts recognized for income tax purposes. The measurement of current and deferred tax assets and liabilities are based on provisions of currently enacted tax laws. The effects of future changes in tax laws or rates are not contemplated.
	As part of the process of preparing our consolidated financial statements, we are required to estimate our income tax expense and tax contingencies in each of the tax jurisdictions in which we operate. This process involves estimating current income tax expense together with assessing temporary differences in the treatment of items for tax purposes versus financial accounting purposes that may create net deferred tax assets and liabilities. We rely on estimates and assumptions in preparing our income tax provision.
	We consider many factors when assessing the likelihood of future realization of our deferred tax assets, including our recent earnings experience by jurisdiction, expectations of future taxable income, and the carryforward periods available to us for tax reporting purposes, as well as other relevant factors. We establish a valuation allowance to reduce deferred tax assets to the amount we believe is more likely than not to be realized. Due to inherent complexities arising from the nature of our businesses, future changes in income tax law, or variances between our actual and anticipated operating results, we make certain judgments and estimates. Therefore, actual income taxes could materially vary from these estimates.
	As part of our accounting for business combinations, a portion of the purchase price was allocated to goodwill and intangible assets. Amortization expenses associated with acquired intangible assets are generally not tax deductible; however, deferred taxes have been recorded for non-deductible amortization expenses as a part of the purchase price allocation. In the event of an impairment charge associated with goodwill, such charges are generally not tax deductible and would increase the effective tax rate in the quarter any impairment is recorded.
	We are subject to periodic audits by the Internal Revenue Service and other taxing authorities. These audits may challenge certain tax positions we have taken, such as the timing and amount of deductions and allocation of taxable income to the various tax jurisdictions. The accounting for income tax contingencies may require significant management judgment in estimating final outcomes. Actual results could differ materially from these estimates and could significantly affect the effective tax rate and cash flows in future years. We have elected to record interest and penalties in the financial statements as a component of income taxes.
Concentrations of Risk	Concentrations of Risk
	Financial instruments that are potentially subject to concentrations of credit risk consist primarily of cash, cash equivalents, marketable securities, and trade receivables. Investment policies have been implemented that limit investments to investment grade securities. The average portfolio maturity is currently less than a year. The risk with respect to trade receivables is mitigated by credit evaluations we perform on our customers and by the diversification of our customer base. One value-added distributor (VAD), Arrow Electronics, Inc. (Arrow) accounted for 16% of our trade receivables balance at December 31, 2014. One VAD, Avnet Inc. (Avnet), and one service provider partner, Orange Business Services, accounted for 17% and 13% of our trade receivables balance as of December 31, 2013, respectively. Two VADs, Arrow and Avnet, represented 20% and 14%, respectively, of our revenue for the year ended December 31, 2014; 18% and 13%, respectively, of our revenue for the year ended December 31, 2013; and 17% and 11% of our revenue for the year ended December 31, 2012.
	We outsource the production of our inventory to third-party manufacturers. We rely on purchase orders or long-term contracts with our contract manufacturers. At December 31, 2014, we had no long-term contractual commitment with any manufacturer; however, we did have 90 day commitments totaling $11.0 million.
Comprehensive Income (loss)	Comprehensive income (loss) is defined as the change in equity during a period from transactions and other events and circumstances from non-owner sources. We include comprehensive income (loss) as part of our consolidated statement of changes in stockholders' equity, the components of which are included in the Statement of Comprehensive Income (Loss). Accumulated other comprehensive income (loss) includes net unrealized gains (losses) on available-for-sale securities, unrealized gains (losses) on derivative instruments that qualify for hedge accounting, and net foreign currency translation gains (losses).
Foreign Currency Translation	Foreign Currency Translation
	While the majority of our revenue contracts are denominated in U.S. dollars, we incur certain operating expenses in various foreign currencies. The functional currency of our foreign operations is generally the local country’s currency. Consequently, expenses of operations outside the U.S. are translated into U.S. dollars using average exchange rates for the period reported while assets and liabilities of operations outside the U.S. are translated into U.S. dollars using end of period exchange rates. Foreign currency translation adjustments not affecting net income (loss) are included in stockholders’ equity as a component of Accumulated other comprehensive income (loss) in the accompanying consolidated balance sheets. The revaluation effect of foreign currency fluctuations on intercompany balances is recorded to foreign currency gain (loss) and included in Interest expense and other, net in the accompanying consolidated statements of operations. Foreign currency gains (losses) included in Interest expense and other, net included for the years ended December 31, 2014, 2013 and 2012, were a loss of $1.3 million, a gain of $0.1 million and a loss of $2.6 million, respectively.
Advertising	Advertising
	Advertising costs are expensed as incurred. Adverting expenses recorded as marketing expenses were $1.7 million, $2.6 million and $3.6 million for the years ended December 31, 2014, 2013 and 2012, respectively.
	Cooperative advertising obligations with customers are accrued and the costs expensed at the time the related revenue is recognized. Cooperative advertising expenses are recorded as marketing expenses to the extent that an advertising benefit separate from the revenue transaction can be identified and the cash paid does not exceed the fair value of that advertising benefit received. Otherwise, such cooperative advertising obligations with customers are recorded as a reduction of revenue. Cooperative advertising expenses recorded as a reduction of revenue were $5.4 million, $6.5 million and $6.5 million in the years ended December 31, 2014, 2013 and 2012, respectively.
Research and Development	Research and Development
	All costs to develop our products are expensed as incurred.
Shipping and Handling Cost Policy	Shipping and Handling Costs
	Our shipping and handling costs for product sales are included in the cost of product revenue for all periods presented.

Organization_And_Significant_A2

Organization And Significant Accounting Policies Organization And Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss)	The amounts reclassified out of Accumulated other comprehensive income (loss) to Net income (loss) are as follows:
	(in thousands)	Unrealized gain (loss) on investments, net of tax			Foreign currency translation adjustment			Derivative instruments gain, net of tax			Total
	Balance as of December 31, 2013	$	(30	)	$	(59	)	$	505		$	416
	Other comprehensive loss before reclassifications	(74		)	(2,144		)	(4,890		)	(7,108		)
	Amounts reclassified from accumulated other comprehensive income (loss)	30			—			998			1,028
	Net current-period other comprehensive loss	(44		)	(2,144		)	(3,892		)	(6,080		)
	Balance at December 31, 2014	$	(74	)	$	(2,203	)	$	(3,387	)	$	(5,664	)

Acquisitions_Tables

Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2014
Business Acquisition [Line Items]
Acquisition-Related Compensation Costs That Were Recognized in Operating Expenses	:
		Year ended December 31,
	(in thousands)	2014		2013		2012
	Transaction costs	$	10,992	$	—	$	12,504
	Integration and acquisition-related costs	5,688		18,322		3,412
	Change in fair value of acquisition-related contingent consideration	—		—		(15,190		)
	Acquisition and disposition-related costs	$	16,680	$	18,322	$	726
Operating Expense [Member]
Business Acquisition [Line Items]
Acquisition-Related Compensation Costs That Were Recognized in Operating Expenses	2014, 2013 and 2012:
	(in thousands)	Year ended December 31,
		2014		2013		2012
	Sales and marketing	$	3	$	486	$	788
	Research and development	99		98		1,807
	General and administrative	—		566		23
	Total acquisition-related compensation costs	102		1,150		2,618
	Acquisition and integration-related recorded in Other costs	16,680		18,322		726
	Total acquisition and disposition-related costs	$	16,782	$	19,472	$	3,344

Net_Income_Per_Common_Share_Ta

Net Income Per Common Share (Tables)	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Computation of Net Income Per Share	The following table sets forth the computation of net income (loss) per share:
	(in thousands, except per share data)	Year ended December 31,
		2014			2013			2012
	Net income (loss)	$	71,268		$	(12,418	)	$	54,597
	Weighted average common shares outstanding — basic	158,680			162,707			156,205
	Dilutive effect of employee stock plans	4,512			—			8,365
	Weighted average common shares outstanding — diluted	163,192			162,707			164,570
	Basic net income (loss) per share	$	0.45		$	(0.08	)	$	0.35
	Diluted net income (loss) per share	$	0.44		$	(0.08	)	$	0.33
Antidilutive Securities Excluded From Computation of Diluted Net Income Per Common Share
	(in thousands)	Year ended December 31,
		2014		2013			2012
	Total potential shares of common stock	12,557		21,717			10,368

Fair_Value_Of_Assets_And_Liabi1

Fair Value Of Assets And Liabilites (Tables)	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair Value Measurements Of Cash, Cash Equivalents And Investments	of December 31, 2014, the fair value of our cash, cash equivalents, investments, derivative assets and liabilities, and borrowings measured on a recurring basis consisted of the following:
	(in thousands)	Total		Level 1		Level 2
	Assets:
	Corporate bonds and notes	$	24,637	$	—	$	24,637
	U.S. government-sponsored enterprise obligations	27,548		—		27,548
	Money market funds	28,283		28,283		—
	Cash	215,916		—		—
	Total cash and cash equivalents	$	296,384	$	28,283	$	52,185
	Corporate bonds and notes	$	75,845	$	—	$	75,845
	U.S. government backed securities	43,736		43,736		—
	U.S. government-sponsored enterprise obligations	178,287		—		178,287
	FDIC-backed certificates of deposit	19,654		—		19,654
	Total investments	$	317,522	$	43,736	$	273,786
	Total assets	$	613,906	$	72,019	$	325,971
	Liabilities:
	Derivative liability	$	2,298	$	—	$	2,298
	Borrowings	$	510,000	$	—	$	510,000
	Total liabilities	$	512,298	$	—	$	512,298
	As of December 31, 2014 and 2013, there were no Level 3 instruments.
	As of December 31, 2013, the fair value measurements of our cash and cash equivalents, investments, derivative assets and liabilities, and borrowings consisted of the following:
	(in thousands)	Total		Level 1		Level 2
	Assets:
	Corporate bonds and notes	$	28,545	$	—	$	28,545
	U.S. government-sponsored enterprise obligations	18,775		—		18,775
	Money market funds	30,009		30,009		—
	Cash	130,693		—		—
	Total cash and cash equivalents	$	208,022	$	30,009	$	47,320
	Corporate bonds and notes	$	74,648	$	—	$	74,648
	U.S. government backed securities	23,210		23,210		—
	U.S. government-sponsored enterprise obligations	211,094		—		211,094
	FDIC-backed certificates of deposit	15,062		—		15,062
	Total investments	$	324,014	$	23,210	$	300,804
	Derivative asset	$	331	$	—	$	331
	Total assets	$	532,367	$	53,219	$	348,455
	Liabilities:
	Derivative liability	$	103	$	—	$	103
	Borrowings	$	525,000	$	—	$	525,000
	Total liabilities	$	525,103	$	—	$	525,103
	Th
Gross Unrealized Gains And Gross Unrealized Losses	following tables present the gross unrealized gains and losses as of December 31, 2014 and 2013:
	(in thousands)	Fair Value		Unrealized		Unrealized
				Gains		Losses
	Corporate bonds and notes	$	100,482	$	—	$	(16	)
	U.S. government backed securities	43,736		4		(29		)
	U.S. government-sponsored enterprise obligations	205,835		16		(103		)
	Total investments at December 31, 2014	$	350,053	$	20	$	(148	)
	Corporate bonds and notes	$	103,193	$	1	$	(24	)
	U.S. government backed securities	23,210		7		(2		)
	U.S. government-sponsored enterprise obligations	229,869		55		(30		)
	FDIC-backed certificates of deposit	15,062		1		—
	Total investments at December 31, 2013	$	371,334	$	64	$	(56	)
	We

Inventory_Tables

Inventory (Tables)	12 Months Ended
	Dec. 31, 2014
Inventory, Gross [Abstract]
Components of Inventory	Inventory is comprised of the following:
	(in thousands)	As of December 31,
		2014		2013
	Raw materials	$	2,387	$	5,069
	Finished goods	11,587		15,430
	Evaluation units	812		4,526
	Total	$	14,786	$	25,025

Goodwill_And_Intangible_Assets1

Goodwill And Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Components Of Goodwill	Goodwill consisted of the following:
	(in thousands)
	Balance at December 31, 2012	$	699,785
	Other adjustments	4,520
	Balance at December 31, 2013	$	704,305
	Disposition of goodwill related to the sale of the SteelStore product line	(19,368		)
	Reclassification to Assets held for sale	(15,221		)
	Balance at December 31, 2014	$	669,716
Components of Intangible Assets	Intangible assets, net, consisted of the following:
	(in thousands)		As of December 31, 2014
			Gross				Accumulated				Net
							Amortization
	Existing technology		$	205,453			$	(92,765	)		$	112,688
	Patents		3,299				(3,049		)		250
	Maintenance agreements		216,800				(63,103		)		153,697
	Customer contracts		49,603				(20,679		)		28,924
	Trademarks		12,500				(5,181		)		7,319
	Non-compete agreements		5,300				(3,634		)		1,666
	Currency translation adjustment		—				—				—
	Total intangible assets, net		$	492,955			$	(188,411	)		$	304,544
	Intangible Assets to be disposed of were included in Assets held for sale on the consolidated balance sheet as of December 31, 2014 and, accordingly, were not included in the table above. The amortization of these intangible assets ceased as of the date they were deemed to be held for sale. Accordingly, our intangible assets as of December 31, 2014 were recorded as:
	(in thousands)
	Intangibles, net		$	304,544
	Assets held for sale		14,386
	Total intangibles assets		$	318,930
			Weighted Average Useful Life		As of December 31, 2013
					Gross				Accumulated				Net
									Amortization
	Existing technology		5.4 years		$	237,353			$	(73,111	)		$	164,242
	Patents		5.1 years		8,799				(5,414		)		3,385
	Maintenance agreements		7.4 years		230,100				(41,353		)		188,747
	Customer contracts		6.3 years		51,103				(13,737		)		37,366
	Trademarks		5.6 years		12,800				(3,561		)		9,239
	Non-compete agreements		3.0 years		5,300				(1,900		)		3,400
	Currency translation adjustment		N/A		—				—				(1,912		)
	Total intangible assets, net				$	545,455			$	(139,076	)		$	404,467
Estimated Future Amortization Expense Related to Intangible Assets	Estimated future amortization expense related to the above intangible assets subject to amortization, excluding those intangibles recorded as Assets held for sale, at December 31, 2014 is as follows:
	Fiscal Year		In thousands
	2015		$	71,609
	2016		68,337
	2017		59,013
	2018		57,795
	2019		27,040
	Thereafter		20,750
	Total remaining amortization of intangibles		$	304,544

Fixed_Assets_Tables

Fixed Assets (Tables)	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Components Of Fixed Assets	Fixed assets consisted of the following:
	(in thousands)	Estimated	As of December 31,
		Useful
		Lives	2014			2013
	Computer hardware and equipment	3 years	$	53,595		$	53,417
	Leasehold improvements	2-5 years	48,840			37,733
	Furniture and fixtures	3-5 years	14,871			10,207
	Software	2-5 years	48,061			38,173
	Total fixed assets		165,367			139,530
	Accumulated depreciation and amortization		(94,567		)	(81,720		)
	Fixed assets, net		$	70,800		$	57,810

Accrued_Liabilities_Tables

Accrued Liabilities (Tables)	12 Months Ended
	Dec. 31, 2014
Accrued Liabilities, Current [Abstract]
Accrued Compensation and Benefits	Accrued compensation and benefits consisted of the following:
	(in thousands)	As of December 31,
		2014		2013
	Accrued commissions	$	12,428	$	14,850
	Vacation liability	$	15,089	$	14,218
	Other accrued compensation and benefits	21,223		22,920
	Total accrued compensation and benefits	$	48,740	$	51,988
Other Current Liabilities [Table Text Block]	Other accrued liabilities consisted of the following:
	(in thousands)	As of December 31,
		2014		2013
	Deferred rent liability	$	36,119	$	12,342
	Other accrued liabilities	26,016		24,178
	Total other accrued liabilities	$	62,135	$	36,520
Schedule of other liabilities, noncurrent	Other long-term liabilities consisted of the following:
	(in thousands)	As of December 31,
		2014		2013
	Other long-term liabilities	$	1,622	$	445
	Unrecognized tax benefit obligation	45,713		48,465
	Total other long-term liabilities	$	47,335	$	48,910

Deferred_Revenue_Tables

Deferred Revenue (Tables)	12 Months Ended
	Dec. 31, 2014
Deferred Revenue [Abstract]
Components Of Deferred Revenue	Deferred revenue consisted of the following:
	(in thousands)	As of December 31,
		2014		2013
	Product	$	40,547	$	58,692
	Support and services	283,191		253,783
	Total deferred revenue	$	323,738	$	312,475
	Reported as:
	Deferred revenue, current	$	219,600	$	217,131
	Liabilities held for sale	9,586		—
	Deferred revenue, non-current	94,552		95,344
	Total deferred revenue	$	323,738	$	312,475

Restructuring_Tables

Restructuring (Tables)	12 Months Ended
	Dec. 31, 2014
Restructuring and Related Activities [Abstract]
Restructuring and Related Costs	Restructuring liabilities, recorded in Other costs on the consolidated statements of operations, consisted of (in thousands):
		Termination Benefits			Excess Facilities			Total
	Balance at December 31, 2012	$	—		$	—		$	—
	Charges in 2013	—			1,873			1,873
	Cash payments	—			(45		)	(45		)
	Balance at December 31, 2013	—			1,828			1,828
	Charges in 2014	4,333			1,113			5,446
	Cash payments	(3,018		)	(682		)	(3,700		)
	Balance at December 31, 2014	$	1,315		$	2,259		$	3,574
	As reported in (in thousands) as of December 31, 2014:
		Termination Benefits			Excess Facilities			Total
	Other accrued liabilities	$	1,315		$	1,359		$	2,674
	Other long-term liabilities	—			900			900
	Total restructuring liability	$	1,315		$	2,259		$	3,574

Lease_Commitments_Tables

Lease Commitments (Tables)	12 Months Ended
	Dec. 31, 2014
Leases [Abstract]
Operating Leases, Future Minimum Commitments	Future minimum commitments for these operating leases in place as of December 31, 2014 with a remaining non-cancelable lease term in excess of one year are as follows:
	(in thousands)	31-Dec-14
	2015	$	28,634
	2016	27,145
	2017	25,303
	2018	23,645
	2019	21,328
	Thereafter	72,249
	Total	$	198,304

Derivative_Financial_Instrumen1

Derivative Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments in Condensed Consolidated Balance Sheet	The fair value of derivative instruments in our consolidated balance sheets was as follows as of December 31, 2014 and 2013:
		As of December 31,
	(in thousands)	2014			2013
	Derivative assets:
	Foreign currency contracts designated as cash flow hedges	$	—		$	162
	Derivatives not designated as hedging instruments	—			169
	Total derivative assets	$	—		$	331
	Derivative liabilities:
	Foreign currency contracts designated as cash flow hedges	$	1,928		$	57
	Derivatives not designated as hedging instruments	370			46
	Total derivative liabilities	$	2,298		$	103
Schedule of Derivative Instruments Designated as Hedging Instruments on Statement of Operations	The effects of derivatives designated as hedging instruments on our consolidated statements of operations were as follows for the years ended December 31, 2014 and 2013:
		Year ended December 31,
	(in thousands)	2014			2013
	Amount of gain (loss) recognized in Accumulated other comprehensive income (loss) on derivatives (effective portion)	$	(5,095	)	$	191
	Amount and location of losses reclassified from Accumulated other comprehensive income (loss) into earnings (effective portion)
	Cost of support and services	$	(130	)	$	(90	)
	Sales and marketing	(829		)	(154		)
	Research and development	(19		)	(36		)
	General and administrative	(20		)	(29		)
	Total	$	(998	)	$	(309	)
	Amount and location of gain recognized in earnings on derivatives (ineffective portion and amount excluded from effectiveness testing)
	Interest expense and other, net	$	214		$	91
Schedule of Derivatives Not Designated as Hedging Instruments, Effect on Statement of Operations	The effects of derivatives not designated as hedging instruments on our consolidated statements of operations were as follows for the year ended December 31, 2014 and 2013:
		Year ended December 31,
	(in thousands)	2014			2013
	Interest expense and other, net	$	(864	)	$	192

Borrowings_Tables

Borrowings (Tables)	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Schedule of Debt Covenant Ratios	must also maintain, at the end of each fiscal quarter, a consolidated leverage ratio of (x) consolidated funded debt to (y) consolidated EBITDA (as defined in the 2013 Credit Facility) as of the last day of any fiscal quarter of the Borrower as set forth in the table below:
	Fiscal Quarter Ending	Consolidated Leverage Ratio
	December 31, 2013 to December 31, 2014	3.50 to 1.00
	March 31, 2015 to December 31, 2015	3.25 to 1.00
	March 31, 2016 and thereafter	3.00 to 1.00
Schedule of Maturities of Borrowings	The following table summarizes the future minimum principal payments on the 2013 Credit Facility outstanding as of December 31, 2014:
	Fiscal year	(in thousands)
	2015	$	15,000
	2016	30,000
	2017	30,000
	2018	435,000
	Thereafter	—
	Total	$	510,000

Common_Stock_Tables

Common Stock (Tables)	12 Months Ended
	Dec. 31, 2014
Share-based Compensation [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant [Table Text Block]	A summary of shares available for grant as of December 31, 2014 is as follows:
	(in thousands)	Year ended December 31,
		2014
	2014 Plan	11,902
	2009 Inducement equity incentive plan	787
	Purchase plan	8,493
	Total	21,182
Summary Of Stock-Based Compensation Expense	The following table summarizes stock-based compensation expense for stock options, RSUs and the Purchase Plan recorded in our statement of operations:
	(in thousands)		Year ended December 31,
			2014				2013			2012
	Cost of product		$	1,461			$	1,212		$	942
	Cost of support and services		8,642				8,832			6,853
	Sales and marketing		36,113				40,991			35,668
	Research and development		28,677				25,183			28,645
	General and administrative		15,614				14,339			17,186
	Total stock-based compensation expense		$	90,507			$	90,557		$	89,294
Assumptions Used To Estimate Fair Value Of Options Granted	The fair value of options granted and Purchase Plan shares granted was estimated at the date of grant using the following assumptions:
			Year ended December 31,
			2014		2013		2012
	Employee Stock Options
	Expected term in years		4.3 - 4.4		4.3 - 4.4		4.2 - 4.3
	Risk-free interest rate		1.3% - 1.4%		0.7% - 1.2%		0.6% - 0.7%
	Volatility		48% - 52%		53% - 63%		62% - 66%
Assumptions Used to Estimate Fair Value of Purchase Plan Shares Granted
			Year ended December 31,
			2014		2013		2012
	Purchase Plan
	Expected term in years		0.5 - 2.0		0.5 - 2.0		0.5 - 2.0
	Risk-free interest rate		0.05% - 0.50%		0.08% - 0.30%		0.14% - 0.29%
	Volatility		22% - 43%		40% - 64%		63% - 74%
Summarized Information About Stock Options Activity	The following table summarizes information about stock options activity under all stock option plans:
	(in thousands, except per share amounts)		Options			Weighted			Weighted Average		Aggregate
			Outstanding			Average			Remaining		Intrinsic Value
						Exercise			Contractual Term
						Price			(in years)
	Balance at December 31, 2013		11,951			$	16.84		3.67		$	48,405
	Granted		134			$	19.77
	Exercised		(3,767	)		$	11.55
	Forfeited or expired		(1,081	)		$	22.55
	Balance at December 31, 2014		7,237			$	18.79		3.29		$	32,783
	Exercisable		5,446			$	18.94		2.7		$	27,225
	Vested and expected to vest		6,999			$	18.8		3.19		$	32,067
Summarized Information About Nonvested RSU's	The following table summarizes information about RSU activity for the year ended as of December 31, 2014:
	(in thousands, except per share amounts)		Number of Shares			Weighted
						Average Grant
						Date Fair Value
	Balance at December 31, 2013		9,126			$	17.67
	Granted		6,488			$	19.31
	Vested		(3,151	)		$	18.96
	Forfeited		(2,548	)		$	17.11
	Balance at December 31, 2014		9,915			$	17.69

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Geographical Breakdown Of Income Before Provision For Income Taxes	A geographical breakdown of income (loss) before provision for (benefit from) income taxes is shown in the following table:
		Year ended December 31,
	(in thousands)	2014			2013			2012
	Domestic	$	44,359		$	(46,884	)	$	50,095
	Foreign	50,511			20,319			43,938
	Total	$	94,870		$	(26,565	)	$	94,033
Provision (Benefit) For Income Tax Expense	The provision for (benefit from) income tax expense consists of the following:
		Year ended December 31,
	(in thousands)	2014			2013			2012
	Current:
	Federal	$	37,482		$	25,396		$	24,105
	State	6,163			2,971			2,629
	Foreign	9,066			6,423			7,267
	Total current	$	52,711		$	34,790		$	34,001
	Deferred:
	Federal	$	(23,719	)	$	(35,731	)	$	6,483
	State	(4,752		)	(12,920		)	917
	Foreign	(638		)	(286		)	(1,965		)
	Total deferred	$	(29,109	)	$	(48,937	)	$	5,435
	Total provision for (benefit from) income taxes	$	23,602		$	(14,147	)	$	39,436
Difference Between Tax Provision And Effective Tax Rate	The difference between the provision for (benefit from) income taxes and the amount computed by applying the federal statutory income tax rate to income before taxes is as follows:
		Year ended December 31,
	(in thousands)	2014			2013			2012
	Expected provision at federal statutory rate	$	33,204		$	(9,298	)	$	32,910
	State taxes, net of federal benefit	788			(6,425		)	2,172
	Stock-based compensation expense	10,212			12,606			9,088
	Intercompany transfers of intellectual property	(4,020		)	3,552			6,614
	Acquisition related expenses	—			—			2,230
	Research and development tax credits	(5,692		)	(8,392		)	(964		)
	Foreign rate differential	(14,012		)	(6,172		)	(11,920		)
	Domestic production activities deduction	(3,221		)	(2,227		)	(299		)
	Meals and entertainment	523			494			400
	Change in uncertain tax positions, including interest	(489		)	1,167			122
	Disposition of non-deductible goodwill related to sale of product line	6,779			—			—
	Other (net)	(470		)	548			(917		)
	Total	$	23,602		$	(14,147	)	$	39,436
Components Of Current And Non-Current Deferred Tax Assets And Liabilities	The components of our deferred tax assets and liabilities consisted of the following:
		As of December 31,
	(in thousands)	2014			2013
	Deferred tax liabilities:
	Depreciation and amortization	$	(8,194	)	$	(4,604	)
	Intangible Assets	(81,637		)	(101,925		)
	Total deferred tax liabilities	$	(89,831	)	$	(106,529	)
	Deferred tax assets:
	Deferred compensation	$	26,702		$	29,863
	Credit carryforwards	20,161			16,763
	Deferred revenue	5,588			915
	Net operating losses	8,631			9,967
	Other accrued liabilities and reserves	31,637			20,809
	State taxes	1,393			3,128
	Total deferred tax assets	$	94,112		$	81,445
	Valuation allowance	$	(19,411	)	$	(16,168	)
	Total net deferred tax liabilities	$	(15,130	)	$	(41,252	)
	The components of our deferred tax assets and liabilities consisted of the following:
	(in thousands)	As of December 31,
		2014			2013
	Current deferred tax assets	$	31,802		$	7,222
	Non-current deferred tax assets	1			74
	Non-current deferred tax liabilities	(46,933		)	(48,548		)
	Net deferred tax liabilities	$	(15,130	)	$	(41,252	)
Reconciliation Of Beginning And Ending Amount Of Consolidated Liability For Unrecognized Income Tax Benefits	A reconciliation of the beginning and ending amount of the consolidated liability for unrecognized income tax benefits during the year is as follows:
		Year ended December 31,
	(in thousands)	2014			2013			2012
	Beginning balance	$	53,115		$	30,690		$	26,995
	Additions for tax positions of prior years	175			2,485			930
	Additions for tax positions related to current year	6,699			21,306			3,810
	Reductions for tax positions of prior year	(8,422		)	(1,351		)	(979		)
	Settlements	—			(15		)	(66		)
	Ending balance	$	51,567		$	53,115		$	30,690

Segment_Information_Tables

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2014
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Schedule of Segment Reporting Information, by Segment [Table Text Block]	The following table presents revenue by product line:
		Year ended December 31,
	(in thousands)	2014		2013		2012
	Application Acceleration	$	831,765	$	807,469	$	767,037
	Performance Management	257,443		233,564		69,823
	Total revenue	$	1,089,208	$	1,041,033	$	836,860
Schedule of Revenue from External Customers Attributed to Foreign Countries by Geographic Area [Table Text Block]	Revenue by Geography
		Year ended December 31,
	(in thousands)	2014		2013		2012
	Americas
	United States	$	621,209	$	611,469	$	463,534
	Other Americas	33,893		38,351		31,373
	Total Americas	655,102		649,820		494,907
	Europe, Middle East and Africa
	United Kingdom	147,069		118,022		124,458
	Other Europe, Middle East and Africa	145,645		140,335		101,194
	Total Europe, Middle East and Africa	292,714		258,357		225,652
	Asia Pacific	141,392		132,856		116,301
	Total revenue	$	1,089,208	$	1,041,033	$	836,860

Organization_And_Significant_A3

Organization And Significant Accounting Policies (Details) (USD $)	3 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 14, 2014
		distributor	distributor
Organization And Significant Accounting Policies [Line Items]
Business Acquisition, Share Price					$21
Inventory write-downs		$8,000,000	$11,200,000	$6,700,000
Service inventory	21,100,000	21,100,000	20,800,000
Capitalized internal use software costs	9,900,000	9,900,000	7,700,000	6,900,000
Amortization expense related to software		8,200,000	6,700,000	4,800,000
Service contract term		90 days
Concentration of risk trade receivable, number of distributors			1
Concentration of risk revenues, number of distributors		2
Purchase commitment period		90 days
90 day commitment	11,000,000	11,000,000
Foreign currency losses		1,300,000	100,000	2,600,000
Advertising expenses		1,700,000	2,600,000	3,600,000
Loss on Contract Termination	126,000,000
Business Combination Transaction Related Costs	4,000,000	10,992,000	0	12,504,000
Minimum [Member]
Organization And Significant Accounting Policies [Line Items]
Support service contract term		1 year
Payment terms to customers		30 days
Maximum [Member]
Organization And Significant Accounting Policies [Line Items]
Support service contract term		3 years
Payment terms to customers		90 days
Restricted Stock Units (RSUs) [Member] | Minimum [Member]
Organization And Significant Accounting Policies [Line Items]
Weighted-average service period		3 years
Restricted Stock Units (RSUs) [Member] | Maximum [Member]
Organization And Significant Accounting Policies [Line Items]
Weighted-average service period		4 years
Stock Options [Member] | Minimum [Member]
Organization And Significant Accounting Policies [Line Items]
Weighted-average service period		3 years
Stock Options [Member] | Maximum [Member]
Organization And Significant Accounting Policies [Line Items]
Weighted-average service period		4 years
Employee Stock [Member] | Minimum [Member]
Organization And Significant Accounting Policies [Line Items]
Weighted-average service period		6 months
Employee Stock [Member] | Maximum [Member]
Organization And Significant Accounting Policies [Line Items]
Weighted-average service period		2 years
Arrow [Member]
Organization And Significant Accounting Policies [Line Items]
Concentration of risk trade receivable, number of distributors	1	1
Concentration of risk trade receivables	16.00%	16.00%
Concentration of risk percentage of revenue		20.00%	18.00%	17.00%
Orange [Member]
Organization And Significant Accounting Policies [Line Items]
Concentration of risk trade receivable, number of distributors			1
Concentration of risk trade receivables			13.00%
Avnet [Member]
Organization And Significant Accounting Policies [Line Items]
Concentration of risk trade receivables			17.00%
Concentration of risk percentage of revenue		14.00%	13.00%	11.00%
Cooperative Advertising [Member]
Organization And Significant Accounting Policies [Line Items]
Cooperative Advertising Amount		$5,400,000	$6,500,000	$6,500,000

Organization_And_Significant_A4

Organization And Significant Accounting Policies (Accumulated Other Comprehensive Income) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance as of December 31, 2013	$416
Other comprehensive loss before reclassifications	-7,108
Amounts reclassified from accumulated other comprehensive income (loss)	1,028
Other Comprehensive Income (Loss), Net of Tax	-6,080	1,684	2,705
Balance at December 31, 2014	-5,664	416
Unrealized gain (loss) on investments, net of tax [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance as of December 31, 2013	-30
Other comprehensive loss before reclassifications	-74
Amounts reclassified from accumulated other comprehensive income (loss)	30
Other Comprehensive Income (Loss), Net of Tax	-44
Balance at December 31, 2014	-74
Foreign currency translation adjustment [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance as of December 31, 2013	-59
Other comprehensive loss before reclassifications	-2,144
Amounts reclassified from accumulated other comprehensive income (loss)	0
Other Comprehensive Income (Loss), Net of Tax	-2,144
Balance at December 31, 2014	-2,203
Derivative instruments gain (loss), net of tax [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance as of December 31, 2013	505
Other comprehensive loss before reclassifications	-4,890
Amounts reclassified from accumulated other comprehensive income (loss)	-998
Other Comprehensive Income (Loss), Net of Tax	-3,892
Balance at December 31, 2014	($3,387)

Acquisitions_Narrative_Details

Acquisitions (Narrative) (Details) (USD $)	12 Months Ended		0 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2012	Dec. 18, 2012	Dec. 31, 2013	Dec. 17, 2012
Business Acquisition [Line Items]
Stock Issued During Period, Value, Acquisitions		$123,231,000
Payments for Merger Related Costs	9,900,000
Opnet Technologies, Inc [Member]
Business Acquisition [Line Items]
Fair value of consideration transferred			980,200,000
Payment to shareholders			857,000,000
Stock Issued During Period, Value, Acquisitions				122,600,000
Business Combination, Consideration Transferred, Options Assumed				600,000
Business Acquisition, Goodwill, Expected Tax Deductible Amount				586,700,000	582,200,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill				458,500,000	458,500,000
Purchase price allocation, deferred tax liabilities				166,100,000	159,300,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net				$101,100,000	$98,800,000

Acquisitions_Summarizes_Of_Acq

Acquisitions (Summarizes Of Acquisition-Related Costs Recognized) (Details) (USD $)	3 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Business Combinations [Abstract]
Transaction costs	$4,000	$10,992	$0	$12,504
Integration costs		5,688	18,322	3,412
Change in fair value of acquisition-related contingent consideration		0	0	-15,190
Acquisition-related costs		$16,680	$18,322	$726

Acquisitions_AcquisitionRelate

Acquisitions (Acquisition-Related Compensation Costs That Were Recognized In Operating Expenses) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Business Acquisition [Line Items]
Sales and marketing	$454,945	$469,200	$328,657
Research and development	205,591	189,654	146,108
General and administrative	76,535	73,339	60,594
Acquisition-related costs	16,680	18,322	726
Acquisition-Related Costs And Compensation Costs [Member]
Business Acquisition [Line Items]
Sales and marketing	3	486	788
Research and development	99	98	1,807
General and administrative	0	566	23
Total other acquisition-related compensation costs	102	1,150	2,618
Acquisition-related costs	16,680	18,322	726
Total acquisition-related costs and acquisition-related compensation costs	$16,782	$19,472	$3,344

Acquisitions_and_Dispositions_

Acquisitions and Dispositions Dispositions Narrative (Details) (USD $)	0 Months Ended	12 Months Ended
	Oct. 27, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Oct. 27, 2014
Significant Acquisitions and Disposals [Line Items]
Disposition of goodwill related to the sale of the SteelStore product line		$19,368,000
Liabilities of Business Transferred under Contractual Arrangement		9,600,000
Revenue, Net		1,089,208,000	1,041,033,000	836,860,000
Finite-Lived Intangible Assets [Member]
Significant Acquisitions and Disposals [Line Items]
Disposal Group, Assets of Business Transferred under Contractual Arrangement		1,400,000
Indefinite-lived Intangible Assets [Member]
Significant Acquisitions and Disposals [Line Items]
Disposal Group, Assets of Business Transferred under Contractual Arrangement		14,400,000
Goodwill [Member]
Significant Acquisitions and Disposals [Line Items]
Disposal Group, Assets of Business Transferred under Contractual Arrangement		15,200,000
SteelStore [Member]
Significant Acquisitions and Disposals [Line Items]
Consideration received	80,000,000				80,000,000
Proceeds from divestiture of businesses	65,800,000
Escrow Deposit	12,000,000				12,000,000
Net assets	21,000,000				21,000,000
Disposition of goodwill related to the sale of the SteelStore product line	19,400,000
Gain on disposition of business	57,400,000
Revenue		4,600,000	4,400,000	2,000,000
SteelApp [Member]
Significant Acquisitions and Disposals [Line Items]
Revenue, Net		$31,100,000	$35,800,000	$28,400,000

Net_Income_Per_Common_Share_Co

Net Income Per Common Share (Computation Of Net Income Per Share) (Details) (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Earnings Per Share [Abstract]
Net income (loss)	$71,268	($12,418)	$54,597
Basic	158,680	162,707	156,205
Dilutive effect of employee stock plans	4,512	0	8,365
Weighted average common shares outstanding - diluted	163,192	162,707	164,570
Basic	$0.45	($0.08)	$0.35
Diluted	$0.44	($0.08)	$0.33

Net_Income_Per_Common_Share_An

Net Income Per Common Share (Antidilutive Securities Excluded From Computation Of Diluted Net Income Per Common Share) (Details)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Earnings Per Share [Abstract]
Total potential anti-dilutive shares of common stock	12,557	21,717	10,368

Fair_Value_Of_Assets_And_Liabi2

Fair Value Of Assets And Liabilites (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Fair Value Disclosures [Abstract]
Investments Other than Temporarily Impaired	$0
Investments in continuous loss position greater than one year	0
Carrying value of cash and cash equivalents	296,384,000	208,022,000	280,509,000	215,476,000
Investments maturity date, maximum	2 years
Current restricted cash	1,600,000	3,300,000
Restricted Cash and Cash Equivalents, Noncurrent	$20,600,000	$9,100,000

Fair_Value_Of_Assets_And_Liabi3

Fair Value Of Assets And Liabilites (Fair Value Measurements Of Cash, Cash Equivalents, Investments, Derivatives, and Borrowings) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Assets:
Total cash and cash equivalents	$296,384	$208,022
Total investments	317,522	324,014
Derivative Asset, Fair Value		331
Assets, Fair Value Disclosure, Recurring	613,906	532,367
Liabilities:
Derivative liability, Fair Value	2,298	103
Long-term Debt, Fair Value		525,000
Total Borrowings, Fair Value Disclosure	510,000
Liabilities, Fair Value Disclosure, Recurring	512,298	525,103
Level 1 [Member]
Assets:
Total cash and cash equivalents	28,283	30,009
Total investments	43,736	23,210
Assets, Fair Value Disclosure, Recurring	72,019	53,219
Liabilities:
Derivative liability, Fair Value	0
Total Borrowings, Fair Value Disclosure	0
Liabilities, Fair Value Disclosure, Recurring	0	0
Level 2 [Member]
Assets:
Total cash and cash equivalents	52,185	47,320
Total investments	273,786	300,804
Derivative Asset, Fair Value		331
Assets, Fair Value Disclosure, Recurring	325,971	348,455
Liabilities:
Derivative liability, Fair Value	2,298	103
Long-term Debt, Fair Value	510,000	525,000
Liabilities, Fair Value Disclosure, Recurring	512,298	525,103
Corporate Bonds And Notes [Member]
Assets:
Total cash and cash equivalents	24,637	28,545
Total investments	75,845	74,648
Corporate Bonds And Notes [Member] | Level 1 [Member]
Assets:
Total cash and cash equivalents	0	0
Total investments	0	0
Corporate Bonds And Notes [Member] | Level 2 [Member]
Assets:
Total cash and cash equivalents	24,637	28,545
Total investments	75,845	74,648
U.S. Government Backed Securities [Member]
Assets:
Total investments	43,736	23,210
U.S. Government Backed Securities [Member] | Level 1 [Member]
Assets:
Total investments	43,736	23,210
U.S. Government Backed Securities [Member] | Level 2 [Member]
Assets:
Total investments	0	0
U.S. Government-Sponsored Enterprise Obligations [Member]
Assets:
Total cash and cash equivalents	27,548	18,775
Total investments	178,287	211,094
U.S. Government-Sponsored Enterprise Obligations [Member] | Level 1 [Member]
Assets:
Total cash and cash equivalents	0	0
Total investments	0	0
U.S. Government-Sponsored Enterprise Obligations [Member] | Level 2 [Member]
Assets:
Total cash and cash equivalents	27,548	18,775
Total investments	178,287	211,094
Money Market Funds [Member]
Assets:
Total cash and cash equivalents	28,283	30,009
Money Market Funds [Member] | Level 1 [Member]
Assets:
Total cash and cash equivalents	28,283	30,009
Money Market Funds [Member] | Level 2 [Member]
Assets:
Total cash and cash equivalents	0	0
FDIC-Backed Certificates Of Deposit [Member]
Assets:
Total investments	19,654	15,062
FDIC-Backed Certificates Of Deposit [Member] | Level 1 [Member]
Assets:
Total investments	0	0
FDIC-Backed Certificates Of Deposit [Member] | Level 2 [Member]
Assets:
Total investments	19,654	15,062
Cash [Member]
Assets:
Total cash and cash equivalents	215,916	130,693
Cash [Member] | Level 1 [Member]
Assets:
Total cash and cash equivalents	0	0
Cash [Member] | Level 2 [Member]
Assets:
Total cash and cash equivalents	$0	$0

Fair_Value_Of_Assets_And_Liabi4

Fair Value Of Assets And Liabilites (Gross Unrealized Gains And Gross Unrealized Losses) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Gross Unrealized Gains (Losses) [Line Items]
Fair Value	$350,053	$371,334
Corporate Bonds And Notes [Member]
Gross Unrealized Gains (Losses) [Line Items]
Fair Value	100,482	103,193
U.S. Government Backed Securities [Member]
Gross Unrealized Gains (Losses) [Line Items]
Fair Value	43,736	23,210
U.S. Government-Sponsored Enterprise Obligations [Member]
Gross Unrealized Gains (Losses) [Line Items]
Fair Value	205,835	229,869
FDIC-Backed Certificates Of Deposit [Member]
Gross Unrealized Gains (Losses) [Line Items]
Fair Value		15,062
Unrealized Gains [Member]
Gross Unrealized Gains (Losses) [Line Items]
Unrealized Gains	20	64
Unrealized Gains [Member] | Corporate Bonds And Notes [Member]
Gross Unrealized Gains (Losses) [Line Items]
Unrealized Gains		1
Unrealized Gains [Member] | U.S. Government Backed Securities [Member]
Gross Unrealized Gains (Losses) [Line Items]
Unrealized Gains	4	7
Unrealized Gains [Member] | U.S. Government-Sponsored Enterprise Obligations [Member]
Gross Unrealized Gains (Losses) [Line Items]
Unrealized Gains	16	55
Unrealized Gains [Member] | FDIC-Backed Certificates Of Deposit [Member]
Gross Unrealized Gains (Losses) [Line Items]
Unrealized Gains		1
Unrealized Losses [Member]
Gross Unrealized Gains (Losses) [Line Items]
Unrealized Losses	-148	-56
Unrealized Losses [Member] | Corporate Bonds And Notes [Member]
Gross Unrealized Gains (Losses) [Line Items]
Unrealized Losses	-16	-24
Unrealized Losses [Member] | U.S. Government Backed Securities [Member]
Gross Unrealized Gains (Losses) [Line Items]
Unrealized Losses	-29	-2
Unrealized Losses [Member] | U.S. Government-Sponsored Enterprise Obligations [Member]
Gross Unrealized Gains (Losses) [Line Items]
Unrealized Losses	($103)	($30)

Inventory_Components_Of_Invent

Inventory (Components Of Inventory) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Inventory, Gross [Abstract]
Raw materials	$2,387	$5,069
Finished goods	11,587	15,430
Evaluation units	812	4,526
Total inventory	$14,786	$25,025

Goodwill_And_Intangible_Assets2

Goodwill And Intangible Assets (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$669,716,000	$704,305,000	$699,785,000
Amortization expense	$85,500,000	$103,000,000	$25,900,000

Goodwill_And_Intangible_Assets3

Goodwill And Intangible Assets (Components Of Goodwill) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Goodwill [Roll Forward]
Beginning Balance	$704,305	$699,785
Other adjustments	-15,221	4,520
Disposition of goodwill related to the sale of the SteelStore product line	-19,368
Ending Balance	$669,716	$704,305

Goodwill_And_Intangible_Assets4

Goodwill And Intangible Assets (Components Of Intangible Assets) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Gross	$545,455	$492,955
Accumulated Amortization	-139,076	-188,411
Net	404,467	304,544
Assets held for sale		14,386
Total intangibles assets		318,930
Existing Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	5 years 4 months 24 days
Gross	237,353	205,453
Accumulated Amortization	-73,111	-92,765
Net	164,242	112,688
Patents [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	5 years 1 month 6 days
Gross	8,799	3,299
Accumulated Amortization	-5,414	-3,049
Net	3,385	250
Maintenance Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	7 years 4 months 24 days
Gross	230,100	216,800
Accumulated Amortization	-41,353	-63,103
Net	188,747	153,697
Customer Contracts [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	6 years 3 months 18 days
Gross	51,103	49,603
Accumulated Amortization	-13,737	-20,679
Net	37,366	28,924
Trademarks [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	5 years 7 months 6 days
Gross	12,800	12,500
Accumulated Amortization	-3,561	-5,181
Net	9,239	7,319
Noncompete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	3 years
Gross	5,300	5,300
Accumulated Amortization	-1,900	-3,634
Net	3,400	1,666
Currency translation adjustment [Member]
Finite-Lived Intangible Assets [Line Items]
Gross	0	0
Accumulated Amortization	0	0
Net	($1,912)	$0

Goodwill_And_Intangible_Assets5

Goodwill And Intangible Assets (Estimated Future Amortization Expense Related To Intangible Assets) (Details) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Goodwill and Intangible Assets Disclosure [Abstract]
2014	$71,609
2015	68,337
2016	59,013
2017	57,795
2018	27,040
Thereafter	20,750
Net Book Value	$304,544

Fixed_Assets_Components_Of_Fix

Fixed Assets (Components Of Fixed Assets) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Total fixed assets	$165,367,000	$139,530,000
Accumulated depreciation and amortization	-94,567,000	-81,720,000
Fixed assets, net	70,800,000	57,810,000
Depreciation and amortization expense	28,200,000	23,200,000	14,600,000
Computer Hardware And Equipment [Member]
Property, Plant and Equipment [Line Items]
Total fixed assets	53,595,000	53,417,000
Estimated Useful Lives	3 years
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Total fixed assets	48,840,000	37,733,000
Furniture And Fixtures [Member]
Property, Plant and Equipment [Line Items]
Total fixed assets	14,871,000	10,207,000
Software [Member]
Property, Plant and Equipment [Line Items]
Total fixed assets	48,061,000	38,173,000
Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	2 years
Minimum [Member] | Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	2 years
Minimum [Member] | Furniture And Fixtures [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	3 years
Minimum [Member] | Software [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	2 years
Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	5 years
Maximum [Member] | Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	5 years
Maximum [Member] | Furniture And Fixtures [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	5 years
Maximum [Member] | Software [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	5 years
Finite-Lived Intangible Assets [Member]
Property, Plant and Equipment [Line Items]
Disposal Group, Assets of Business Transferred under Contractual Arrangement	$1,400,000

Accrued_Liabilities_Accrued_Co

Accrued Liabilities (Accrued Compensation And Benefits) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Accrued Liabilities, Current [Abstract]
Accrued commissions	$12,428	$14,850
Payroll withholding taxes	15,089	14,218
Other accrued compensation and benefits	21,223	22,920
Total accrued compensation and benefits	$48,740	$51,988

Accrued_Liabilities_Schedule_o

Accrued Liabilities Schedule of other long-term liabilities (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of other long-term liabilities [Abstract]
Deferred rent liability	$36,119	$12,342
Other accrued liabilities	26,016	24,178
Total other accrued liabilities	62,135	36,520
Other long-term liabilities	1,622	445
Unrecognized tax benefit obligation	45,713	48,465
Total other long-term liabilities	$47,335	$48,910

Deferred_Revenue_Components_Of

Deferred Revenue (Components Of Deferred Revenue) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Deferred Revenue Arrangement [Line Items]
Liabilities of Business Transferred under Contractual Arrangement	$9,600,000
Deferred revenue, current	219,600,000	217,131,000
Disposal Group, Including Discontinued Operation, Liabilities	9,586,000	0
Deferred revenue, non-current	94,552,000	95,344,000
Total deferred revenue	323,738,000	312,475,000
Product [Member]
Deferred Revenue Arrangement [Line Items]
Total deferred revenue	40,547,000	58,692,000
Support And Services [Member]
Deferred Revenue Arrangement [Line Items]
Total deferred revenue	$283,191,000	$253,783,000

Restructuring_Details

Restructuring (Details) (USD $)	3 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2013
	employee
Restructuring Reserve [Roll Forward]
Other accrued liabilities	$62,135,000	$62,135,000	$36,520,000
2013-2014 Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Costs		5,200,000
Number of Positions Eliminated	80
Positions Eliminated, Period Percent	3.00%
Restructuring Reserve [Roll Forward]
Restructuring Reserve		1,828,000	0
Restructuring Charges		5,446,000	1,873,000
Payments for Restructuring		-3,700,000	-45,000
Restructuring Reserve	3,574,000	3,574,000	1,828,000
Other accrued liabilities	2,674,000	2,674,000
Liabilities, Other than Long-term Debt, Noncurrent	900,000	900,000
Restructuring Reserve	3,574,000	3,574,000	1,828,000
Termination Benefits [Member] | 2013-2014 Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Costs		4,300,000
Restructuring Reserve [Roll Forward]
Restructuring Reserve		0	0
Restructuring Charges		4,333,000	0
Payments for Restructuring		-3,018,000	0
Restructuring Reserve	1,315,000	1,315,000	0
Other accrued liabilities	1,315,000	1,315,000
Liabilities, Other than Long-term Debt, Noncurrent	0	0
Restructuring Reserve	1,315,000	1,315,000	0
Excess Facilities [Member] | 2013-2014 Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Costs		900,000
Restructuring Reserve [Roll Forward]
Restructuring Reserve		1,828,000	0
Restructuring Charges		1,113,000	1,873,000
Payments for Restructuring		-682,000	-45,000
Restructuring Reserve	2,259,000	2,259,000	1,828,000
Other accrued liabilities	1,359,000	1,359,000
Liabilities, Other than Long-term Debt, Noncurrent	900,000	900,000
Restructuring Reserve	2,259,000	2,259,000	1,828,000
Opnet Technologies, Inc [Member] | Excess Facilities [Member] | 2013-2014 Plan [Member]
Restructuring Reserve [Roll Forward]
Restructuring Charges			$1,900,000

Lease_Commitments_Details

Lease Commitments (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Leases [Abstract]
2015	$28,634,000
2016	27,145,000
2017	25,303,000
2018	23,645,000
2019	21,328,000
Thereafter	72,249,000
Total	198,304,000
Rent expense under operating leases	$27,800,000	$22,500,000	$13,600,000

Derivative_Financial_Instrumen2

Derivative Financial Instruments (Narrative) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative, Notional Amount	$71.40	$49
Foreign Currency Derivative Instruments Not Designated as Hedging Instruments at Fair Value, Net	$13.20	$11.70

Derivative_Financial_Instrumen3

Derivative Financial Instruments Fair Value of Derivative Instruments, Balance Sheet (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Derivative [Line Items]
Derivative Assets	$0	$331
Derivative Liabilities	2,298	103
Foreign currency contracts designated as cash flow hedges
Derivative [Line Items]
Derivative Assets	0	162
Derivative Liabilities	1,928	57
Derivatives not designated as hedging instruments
Derivative [Line Items]
Derivative Assets	0	169
Derivative Liabilities	$370	$46

Derivative_Financial_Instrumen4

Derivative Financial Instruments (Fair Value of Derivative Instruments, Statement of Income) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain recognized in Accumulated OCI on derivatives (effective portion)	($5,095)	$191
Amount and location of loss reclassified from Accumulated OCI into Income (effective portion)	-998	-309
Cost of support and services
Derivative Instruments, Gain (Loss) [Line Items]
Amount and location of loss reclassified from Accumulated OCI into Income (effective portion)	-130	-90
Sales And Marketing [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount and location of loss reclassified from Accumulated OCI into Income (effective portion)	-829	-154
Research and Development
Derivative Instruments, Gain (Loss) [Line Items]
Amount and location of loss reclassified from Accumulated OCI into Income (effective portion)	-19	-36
General and Administrative
Derivative Instruments, Gain (Loss) [Line Items]
Amount and location of loss reclassified from Accumulated OCI into Income (effective portion)	-20	-29
Other Income (expense), net
Derivative Instruments, Gain (Loss) [Line Items]
Amount and location of gain recognized in Income on derivatives (ineffective portion and amount excluded from effectiveness testing)	$214	$91

Derivative_Financial_Instrumen5

Derivative Financial Instruments (Effects of Derivatives not Designated as Hedges) (Details) (Derivatives not designated as hedging instruments, Other Income [Member], USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Derivatives not designated as hedging instruments | Other Income [Member]
Derivative [Line Items]
Other income (expense), net	($864)	$192

Borrowings_Details

Borrowings (Details) (USD $)	1 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 20, 2013
Debt Instrument [Line Items]
Loan outstanding		$510,000,000
Interest coverage ratio (as a ratio)		3.5
Debt issuance cost	4,200,000
Interest expense, debt		11,100,000	23,700,000
Write off of deferred debt issuance costs		0	12,269,000	0
Maturities of Long-term Debt [Abstract]
2015		15,000,000
2016		30,000,000
2017		30,000,000
2018		435,000,000
Thereafter		0
Total		510,000,000
2013 Credit Facility [Member]
Debt Instrument [Line Items]
Debt instrument, face amount		600,000,000
Revolving credit facility, maximum borrowing capacity		300,000,000
Loan term	5 years
Revolving credit facility, amount outstanding					225,000,000
Future annual payments, stated rate (as a percent)		5.00%
Senior Secured Term Loan [Member] | 2013 Credit Facility [Member]
Debt Instrument [Line Items]
Debt instrument, face amount		300,000,000
Loan outstanding					300,000,000
Maturities of Long-term Debt [Abstract]
Total					$300,000,000
Minimum [Member] | 2013 Credit Facility [Member]
Debt Instrument [Line Items]
Commitment fee percentage (as a percent)	0.25%
Maximum [Member] | 2013 Credit Facility [Member]
Debt Instrument [Line Items]
Commitment fee percentage (as a percent)	0.30%
LIBOR [Member] | 2013 Credit Facility [Member]
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)		1.75%
Stated rate (as a percent)		2.00%
LIBOR [Member] | Minimum [Member] | 2013 Credit Facility [Member]
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)		1.25%
LIBOR [Member] | Maximum [Member] | 2013 Credit Facility [Member]
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)		2.00%
Prime Rate [Member] | Minimum [Member] | 2013 Credit Facility [Member]
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)		0.25%
Prime Rate [Member] | Maximum [Member] | 2013 Credit Facility [Member]
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)		1.00%

Borrowings_Covenant_Compliance

Borrowings (Covenant Compliance Ratios) (Details) (2013 Credit Facility [Member])	12 Months Ended
	Dec. 31, 2014
December 31, 2013 to December 31, 2014 [Member]
Debt Instrument [Line Items]
Consolidated Leverage Ratio	3.5
March 31, 2015 to December 31, 2015 [Member]
Debt Instrument [Line Items]
Consolidated Leverage Ratio	3.25
Debt Instrument, Redemption, Period Three [Member]
Debt Instrument [Line Items]
Consolidated Leverage Ratio	3

Common_Stock_Narrative_Details

Common Stock (Narrative) (Details) (USD $)	0 Months Ended	12 Months Ended	0 Months Ended			12 Months Ended
In Millions, except Share data, unless otherwise specified	Nov. 11, 2013	Dec. 31, 2014	22-May-13	Aug. 19, 2013	17-May-12	Dec. 31, 2013	Dec. 31, 2012	Nov. 21, 2013	Nov. 10, 2013	Aug. 19, 2011
									right
Class of Stock [Line Items]
Dividends distribution, number of rights per outstanding share									1
Preferred stock, par value		0.0001				$0.00		$0.00
Percent ownership threshold of common stock to become exercisable	10.00%
Percent ownership threshold of common stock to become exercisable for certain institutional investors	20.00%
Right to purchase preferred stock, exercise price (USD per share)								$75,000
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased		192,200,000
2014 Plan [Member]
Class of Stock [Line Items]
Additional shares authorized, in shares		1,631,762
Employee Stock [Member]
Class of Stock [Line Items]
Additional shares authorized, in shares		1,500,000	10,000,000
Percentage of common stock outstanding		1.00%
Share Repurchase Program [Member]
Class of Stock [Line Items]
Share repurchase program, authorized amount										$150
Stock repurchase program, increased authorized amount				200	150
Number of common stock shares repurchased		10,165,000				12,417,000	7,377,000
Value of common stock shares repurchased		195.6				200.1	127.1
Weighted average purchase price per share		19.24				$16.11	$17.24
Stock Options [Member]
Class of Stock [Line Items]
Option vesting, percentage		25.00%
Unrecognized compensation cost		14.9
Weighted-average service period		2 years 0 months
Aggregate intrinsic value of stock option awards exercised		31.2				37.8	45.9
Weighted average grant-date fair value		7.53				$6.30	$10.19
Restricted Stock Units [Member]
Class of Stock [Line Items]
Award vesting period		3 years
Unrecognized compensation cost		126.3
Weighted-average service period		2 years 6 months 29 days
Shares granted, weighted average grant date fair value (usd per share)		19.31				$16.94	$20.85
Employee Stock [Member]
Class of Stock [Line Items]
Unrecognized compensation cost		7
Weighted average grant-date fair value		5.69				$5.85	$8.67
Common stock purchase by employee lesser of fair market value		85.00%
Offering period under stock repurchase plan (in months)		24 months
Purchase period under stock repurchase plan (in months)		6 months
Maximum employee payroll deductions		15.00%
Maximum shares can purchase by employee		4,000
Remaining purchase plan offering period (in months)		22 months
Minimum [Member]
Class of Stock [Line Items]
Requisite service period		3 years
Minimum [Member] | Restricted Stock Units [Member]
Class of Stock [Line Items]
Award vesting period		3 years
Maximum [Member]
Class of Stock [Line Items]
Requisite service period		4 years
Maximum [Member] | Stock Options [Member]
Class of Stock [Line Items]
Award vesting period		10 years
Maximum [Member] | Stock Options [Member] | Two Thousand Two Plan Prior To May Thirty First Two Thousand Six [Member]
Class of Stock [Line Items]
Award vesting period		10 years
Maximum [Member] | Stock Options [Member] | Two Thousand Nine Plan [Member]
Class of Stock [Line Items]
Award vesting period		7 years
Maximum [Member] | Stock Options [Member] | Two Thousand Two Plan After May Thirty One Two Thousand Six [Member]
Class of Stock [Line Items]
Award vesting period		7 years
Maximum [Member] | Stock Options [Member] | Two Thousand Six Director Plan Before March Four Two Thousand Eight [Member]
Class of Stock [Line Items]
Award vesting period		10 years
Maximum [Member] | Stock Options [Member] | Two Thousand Six Director Plan After March Four Two Thousand Eight [Member]
Class of Stock [Line Items]
Award vesting period		7 years
Maximum [Member] | Stock Options [Member] | Two Thousand Six Plan [Member]
Class of Stock [Line Items]
Award vesting period		7 years
Maximum [Member] | Restricted Stock Units [Member]
Class of Stock [Line Items]
Award vesting period		4 years

Common_Stock_Summary_Of_StockB

Common Stock (Summary Of Stock-Based Compensation Expense) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$90,507	$90,557	$89,294
Cost of product [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	1,461	1,212	942
Cost of support and services [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	8,642	8,832	6,853
Sales and marketing [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	36,113	40,991	35,668
Research and development [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	28,677	25,183	28,645
General and administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$15,614	$14,339	$17,186

Common_Stock_Assumptions_Used_

Common Stock (Assumptions Used To Estimate Fair Value Of Options Granted And Purchase Plan Shares) (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate minimum	0.70%	0.60%	0.80%
Risk-free interest rate maximum	1.20%	0.70%	1.70%
Volatility Minimum	53.00%	62.00%	62.00%
Volatility Maximum	63.00%	66.00%	67.00%
Stock Option [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life in years	4 years 3 months	4 years 2 months 12 days	4 years 2 months 12 days
Stock Option [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life in years	4 years 4 months 24 days	4 years 3 months 18 days	4 years 2 months 12 days
Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate minimum	0.08%	0.14%	0.05%
Risk-free interest rate maximum	0.30%	0.29%	0.56%
Volatility Minimum	40.00%	63.00%	49.00%
Volatility Maximum	64.00%	74.00%	77.00%
Purchase Plan [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life in years	6 months	6 months	6 months
Purchase Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life in years	2 years	2 years	2 years

Common_Stock_Summarized_Inform

Common Stock (Summarized Information About Stock Options Activity) (Details) (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Balance, December 31, 2013, Options Outstanding (in shares)	11,951
Granted, Options Outstanding (in shares)	134
Exercised, Options Outstanding (in shares)	-3,767
Forfeited or expired, Options Outstanding (in shares)	-1,081
Balance, December 31, 2014, Options Outstanding (in shares)	7,237	11,951
Exercisable, Options Outstanding (in shares)	5,446
Vested and expected to vest, Options Outstanding (in shares)	6,999
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Balance, December 31, 2013, Weighted Average Exercise Price (usd per share)	$16.84
Granted, Weighted Average Exercise Price (usd per share)	$19.77
Exercised, Weighted Average Exercise Price (usd per share)	$11.55
Forfeited or expired, Weighted Average Exercise Price (usd per share)	$22.55
Balance, December 31, 2014, Weighted Average Exercise Price (usd per share)	$18.79	$16.84
Exercisable, Weighted Average Exercise Price (usd per share)	$18.94
Vested and expected to vest, Weighted Average Exercise Price (usd per share)	$18.80
Balance, December 31, 2013, Weighted Average Remaining Contractual Term (in years)	3 years 3 months 15 days	3 years 8 months
Balance, December 31, 2014, Weighted Average Remaining Contractual Term (in years)	3 years 3 months 15 days	3 years 8 months
Exercisable, Weighted Average Remaining Contractual Term (in years)	2 years 7 months 41 days
Vested and expected to vest, Weighted Average Remaining Contractual Term (in years)	3 years 2 months 9 days
Balance, December 31, 2013, Aggregate Intrinsic Value	$48,405
Balance, December 31, 2014, Aggregate Intrinsic Value	32,783	48,405
Exercisable, Aggregate Intrinsic Value	27,225
Vested and expected to vest, Aggregate Intrinsic Value	$32,067

Common_Stock_Summarized_Inform1

Common Stock (Summarized Information About Nonvested RSUs) (Details) (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Balance, December 31, 2013, Number of Shares	9,126
Granted, Number of Shares	6,488
Vested, Number of Shares	-3,151
Forfeited, Number of Shares	-2,548
Balance, December 31, 2014, Number of Shares	9,915
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Balance, December 31, 2012, Weighted Average Grant Date Fair Value (usd per share)	$17.67
Vested, Weighted Average Grant Date Fair Value (usd per share)	$18.96
Forfeited, Weighted Average Grant Date Fair Value (usd per share)	$17.11
Balance, December 31, 2013, Weighted Average Grant Date Fair Value (usd per share)	$17.69

Common_Stock_Common_Stock_Shar

Common Stock Common Stock (Shares available for issuance) (Details)	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	21,182,000
Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	8,493,000
2014 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	11,902,000
Two Thousand Nine Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	787,000

Income_Taxes_Narrative_Details

Income Taxes (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Taxes [Line Items]
Effective tax rate	24.90%	53.30%	41.90%
Undistributed earnings of foreign subsidiaries	$159,400,000
Income tax provision (benefit)	23,602,000	-14,147,000	39,436,000
Income Tax Reconciliation, Tax Credits, Research	5,692,000	8,392,000	964,000
Additional income tax expense	12,600,000	10,500,000
Deferred Federal Income Tax Expense (Benefit)	-23,719,000	-35,731,000	6,483,000
Net operating loss carryforwards, federal	22,500,000
Net operating loss carryforwards, state	4,900,000
Net operating loss carryforwards, foreign	1,400,000
Increases (decreases) in taxes payable for the excess tax benefits from stock plans	2,300,000
Income taxes payable	2,265,000	-3,022,000	20,176,000
Unrecorded excess tax benefits resulting from exercise of stock options	5,900,000
Unrecognized tax benefits	51,567,000	53,115,000	30,690,000	26,995,000
Unrecognized tax benefits that would impact effective tax rate if recognized	39,800,000	43,400,000	21,900,000
Unrecognized tax benefits, accrued interest and penalties	2,200,000	1,800,000	500,000
Income tax penalties and interest expense related to uncertain tax positions	700,000	1,100,000	200,000
Reductions in unrecognized tax benefits over the next 12 months	14,500,000
Unrecognzed Tax Benefit, Noncurrent	53,800,000
Unrecognized tax benefits, uncertain tax positions	45,713,000	48,465,000
Federal [Member]
Income Taxes [Line Items]
Income Tax Reconciliation, Tax Credits, Research		4,400,000
Research and development tax credit carryforwards	500,000
State [Member]
Income Taxes [Line Items]
Income tax benefit due to change in tax status	4,400,000
Research and development tax credit carryforwards	32,900,000
Foreign [Member]
Income Taxes [Line Items]
Income tax provision (benefit)	1,700,000	3,800,000
Income tax benefit, per diluted share (usd per share)	$0.01	$0.02
Minimum [Member]
Income Taxes [Line Items]
Open tax years by jurisdiction	2011
Maximum [Member]
Income Taxes [Line Items]
Open tax years by jurisdiction	2013
Other Liabilities [Member]
Income Taxes [Line Items]
Unrecognized tax benefits, uncertain tax positions	45,700,000
Deferred Tax Asset [Member]
Income Taxes [Line Items]
Unrecognized tax benefits, uncertain tax positions	$8,100,000

Income_Taxes_Geographical_Brea

Income Taxes (Geographical Breakdown Of Income Before Provision For Income Taxes) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Domestic	$44,359	($46,884)	$50,095
Foreign	50,511	20,319	43,938
Income (loss) before provision for (benefit from) income taxes	$94,870	($26,565)	$94,033

Income_Taxes_Provision_Benefit

Income Taxes (Provision (Benefit) For Income Tax Expense) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Federal, Current	$37,482	$25,396	$24,105
State, Current	6,163	2,971	2,629
Foreign, Current	9,066	6,423	7,267
Total Current	52,711	34,790	34,001
Federal, Deferred	-23,719	-35,731	6,483
State, Deferred	-4,752	-12,920	917
Foreign, Deferred	-638	-286	-1,965
Total Deferred	-29,109	-48,937	5,435
Total provision (benefit)	$23,602	($14,147)	$39,436

Income_Taxes_Difference_Betwee

Income Taxes (Difference Between Tax Provision And Effective Tax Rate) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Expected provision at federal statutory rate	$33,204	($9,298)	$32,910
State taxes, net of federal benefit	788	-6,425	2,172
Stock-based compensation expense	10,212	12,606	9,088
Amortization of taxes on intercompany sales	-4,020	3,552	6,614
Acquisition related expenses	0	0	2,230
Research and development tax credits	-5,692	-8,392	-964
Foreign rate differential	-14,012	-6,172	-11,920
Manufacturing deduction	-3,221	-2,227	-299
Meals and entertainment	523	494	400
Change in uncertain tax positions, including interest	-489	1,167	122
Goodwill, Written off Related to Sale of Business Unit	6,779	0	0
Other (net)	-470	548	-917
Total provision (benefit)	$23,602	($14,147)	$39,436

Income_Taxes_Components_Of_Cur

Income Taxes (Components Of Current And Non-Current Deferred Tax Assets And Liabilities) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Valuation Allowance [Line Items]
Current deferred tax assets	$31,802	$7,222
State taxes	4,900
Total current deferred tax assets, net	31,802	7,222
Deferred Tax Liabilities, Net	-15,130	-41,252
Non-current deferred tax assets	1	74
Non-current deferred tax liabilities	-46,933	-48,548
Current deferred tax assets (liabilities) [Member]
Valuation Allowance [Line Items]
Depreciation and amortization	-8,194	-4,604
Intangible Assets	-81,637	-101,925
Total deferred tax liabilities	-89,831	-106,529
Non-current deferred tax assets (liabilities) [Member]
Valuation Allowance [Line Items]
Deferred compensation	26,702	29,863
Credit carryforwards	20,161	16,763
Deferred revenue	5,588	915
Net operating losses	8,631	9,967
Other accrued liabilities and reserves	31,637	20,809
State taxes	1,393	3,128
Deferred Tax Assets, Gross	94,112	81,445
Valuation allowance	$19,411	$16,168

Income_Taxes_Reconciliation_Of

Income Taxes (Reconciliation Of Beginning And Ending Amount Of Consolidated Liability For Unrecognized Income Tax Benefits) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning Balance	$53,115	$30,690	$26,995
Additions for tax positions of prior years	175	2,485	930
Additions for tax positions related to the current year	6,699	21,306	3,810
Reductions for tax positions of prior year	-8,422	-1,351	-979
Settlements	0	-15	-66
Ending Balance	$51,567	$53,115	$30,690

Segment_Information_Segment_In

Segment Information (Segment Information, Revenue By Geographic Area) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Total revenue	$1,089,208	$1,041,033	$836,860
United States [Member]
Segment Reporting Information [Line Items]
Total revenue	621,209	611,469	463,534
Other Americas [Member]
Segment Reporting Information [Line Items]
Total revenue	33,893	38,351	31,373
Total Americas [Member]
Segment Reporting Information [Line Items]
Total revenue	655,102	649,820	494,907
United Kingdom [Member]
Segment Reporting Information [Line Items]
Total revenue	147,069	118,022	124,458
Other Europe, Middle East And Africa [Member]
Segment Reporting Information [Line Items]
Total revenue	145,645	140,335	101,194
Total Europe, Middle East And Africa [Member]
Segment Reporting Information [Line Items]
Total revenue	292,714	258,357	225,652
Asia Pacific [Member]
Segment Reporting Information [Line Items]
Total revenue	$141,392	$132,856	$116,301

Segment_Information_Revenue_by

Segment Information Revenue by product line (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenue by product line [Line Items]
Revenue, Net	$1,089,208	$1,041,033	$836,860
Application Acceleration [Member]
Revenue by product line [Line Items]
Revenue, Net	831,765	807,469	767,037
Performance Management [Member]
Revenue by product line [Line Items]
Revenue, Net	$257,443	$233,564	$69,823

Employee_Benefit_Plan_Details

Employee Benefit Plan (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
General Discussion of Pension and Other Postretirement Benefits [Abstract]
Employer contribution	$8.10	$7.80	$5.10

Legal_Matters_Legal_Matters_De

Legal Matters Legal Matters (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Loss Contingencies [Line Items]
Transaction with agency of federal government, amount	$19
Zeus Technology, Ltd. [Member]
Loss Contingencies [Line Items]
Contingent consideration disputed amount		$27

Subsequent_Event_Subsequent_Ev

Subsequent Event Subsequent Event (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Subsequent Event [Line Items]
Revenue, Net	$1,089,208	$1,041,033	$836,860
SteelApp [Member]
Subsequent Event [Line Items]
Revenue, Net	$31,100	$35,800	$28,400

Valuation_and_Qualifying_Accou1

Valuation and Qualifying Accounts (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	$1,544	$1,996	$2,064	$1,586
Additions charged to operations	24	919	825
Write-offs	-476	-987	-347
Ending balance	$1,544	$1,996	$2,064	$1,586