$FSLY
Fastly, Inc. Stock $fsly

$fsly Overview Financials Valuation SEC Filings Company Website

2021 Q4 Form 10-K Financial Statement

#000151741322000038 Filed on March 01, 2022

Income Statement

Concept	2021 Q4	2021	2020 Q4
Revenue	$97.72M	$354.3M	$82.65M
YoY Change	18.23%	21.82%	40.23%
Cost Of Revenue	$47.94M	$167.0M	$33.75M
YoY Change	42.06%	39.16%	32.2%
Gross Profit	$49.77M	$187.3M	$48.90M
YoY Change	1.79%	9.63%	46.36%
Gross Profit Margin	50.94%	52.87%	59.17%
Selling, General & Admin	$69.73M	$279.5M	$67.25M
YoY Change	3.69%	37.5%	94.98%
% of Gross Profit	140.1%	149.2%	137.53%
Research & Development	$35.00M	$126.9M	$25.59M
YoY Change	36.76%	69.57%	97.61%
% of Gross Profit	70.31%	67.72%	52.33%
Depreciation & Amortization	$13.40M	$28.80M	$10.65M
YoY Change	25.8%	44.15%	119.14%
% of Gross Profit	26.92%	15.37%	21.78%
Operating Expenses	$106.4M	$406.3M	$93.94M
YoY Change	13.29%	46.13%	98.02%
Operating Profit	-$56.66M	-$219.0M	-$45.04M
YoY Change	25.79%	104.29%	221.03%
Interest Expense	-$1.041M	$5.245M	-$270.0K
YoY Change	285.56%	238.61%	-157.45%
% of Operating Profit
Other Income/Expense, Net	$201.0K	$356.0K	-$700.0K
YoY Change	-128.71%	-227.6%	250.0%
Pretax Income	-$57.50M	-$222.6M	-$58.32M
YoY Change	-1.41%	107.27%	323.84%
Income Tax	$25.00K	$100.0K	-$12.61M
% Of Pretax Income
Net Earnings	-$57.52M	-$222.7M	-$45.70M
YoY Change	25.87%	132.14%	224.8%
Net Earnings / Revenue	-58.86%	-62.85%	-55.29%
Basic Earnings Per Share		-$1.92
Diluted Earnings Per Share	-$486.4K	-$1.92	-$404.5K
COMMON SHARES
Basic Shares Outstanding	117.5M shares	116.1M shares
Diluted Shares Outstanding		116.1M shares

Balance Sheet

Concept	2021 Q4	2021	2020 Q4
SHORT-TERM ASSETS
Cash & Short-Term Investments	$527.9M	$527.9M	$194.2M
YoY Change	171.84%	171.81%	48.11%
Cash & Equivalents	$166.1M	$31.29M	$62.90M
Short-Term Investments	$361.8M	$361.8M	$131.3M
Other Short-Term Assets	$32.16M	$32.16M	$16.80M
YoY Change	91.43%	91.43%	-79.28%
Inventory
Prepaid Expenses
Receivables	$64.63M	$64.63M	$50.26M
Other Receivables	$0.00	$0.00	$0.00
Total Short-Term Assets	$624.6M	$624.6M	$261.3M
YoY Change	139.09%	139.05%	4.79%
LONG-TERM ASSETS
Property, Plant & Equipment	$167.0M	$236.6M	$95.98M
YoY Change	73.96%	51.66%	59.87%
Goodwill	$636.8M		$635.6M
YoY Change	0.19%		170757.53%
Intangibles	$102.6M		$121.7M
YoY Change	-15.73%		10721.51%
Long-Term Investments	$528.9M	$528.9M
YoY Change
Other Assets	$29.47M	$29.38M	$24.92M
YoY Change	18.26%	-34.71%	146.41%
Total Long-Term Assets	$1.534B	$1.534B	$958.7M
YoY Change	60.05%	60.05%	1238.1%
TOTAL ASSETS
Total Short-Term Assets	$624.6M	$624.6M	$261.3M
Total Long-Term Assets	$1.534B	$1.534B	$958.7M
Total Assets	$2.159B	$2.159B	$1.220B
YoY Change	76.98%	76.97%	280.08%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$9.257M	$9.257M	$9.150M
YoY Change	1.17%	0.62%	98.83%
Accrued Expenses	$36.11M	$66.97M	$34.33M
YoY Change	5.18%	31.05%	72.72%
Deferred Revenue	$26.42M		$15.92M
YoY Change	66.0%		4920.82%
Short-Term Debt	$0.00	$0.00	$0.00
YoY Change
Long-Term Debt Due	$0.00	$21.13M	$11.00M
YoY Change	-100.0%	92.05%	145.97%
Total Short-Term Liabilities	$131.9M	$131.9M	$94.09M
YoY Change	40.16%	40.14%	153.47%
LONG-TERM LIABILITIES
Long-Term Debt	$933.2M	$955.5M	$0.00
YoY Change		6399.99%	-100.0%
Other Long-Term Liabilities	$2.583M	$57.70M	$4.400M
YoY Change	-41.3%	17.03%	323.89%
Total Long-Term Liabilities	$935.8M	$1.013B	$4.400M
YoY Change	21167.91%	1483.12%	-79.17%
TOTAL LIABILITIES
Total Short-Term Liabilities	$131.9M	$131.9M	$94.09M
Total Long-Term Liabilities	$935.8M	$1.013B	$4.400M
Total Liabilities	$1.145B	$1.145B	$158.1M
YoY Change	624.33%	624.27%	149.67%
SHAREHOLDERS EQUITY
Retained Earnings	-$510.9M		-$288.2M
YoY Change	77.27%		50.09%
Common Stock	$2.000K		$2.000K
YoY Change	0.0%		0.0%
Preferred Stock
YoY Change
Treasury Stock (at cost)
YoY Change
Treasury Stock Shares
Shareholders Equity	$1.014B	$1.014B	$1.062B
YoY Change
Total Liabilities & Shareholders Equity	$2.159B	$2.159B	$1.220B
YoY Change	76.98%	76.97%	280.08%

Cashflow Statement

Concept	2021 Q4	2021	2020 Q4
OPERATING ACTIVITIES
Net Income	-$57.52M	-$222.7M	-$45.70M
YoY Change	25.87%	132.14%	224.8%
Depreciation, Depletion And Amortization	$13.40M	$28.80M	$10.65M
YoY Change	25.8%	44.15%	119.14%
Cash From Operating Activities	-$7.908M	-$38.48M	-$31.15M
YoY Change	-74.61%	93.22%	917.97%
INVESTING ACTIVITIES
Capital Expenditures	-$6.729M	$34.82M	-$7.170M
YoY Change	-6.15%	17.74%	22.56%
Acquisitions		$1.169M
YoY Change		-99.42%
Other Investing Activities	-$103.9M	-$744.1M	-$260.3M
YoY Change	-60.06%	213.3%	-779.18%
Cash From Investing Activities	-$110.7M	-$794.5M	-$267.4M
YoY Change	-58.62%	188.89%	-923.37%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net		$0.00
YoY Change		-100.0%
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	2.603M	$936.6M	-17.58M
YoY Change	-114.81%	243.39%	-1010.88%
NET CHANGE
Cash From Operating Activities	-7.908M	-$38.48M	-31.15M
Cash From Investing Activities	-110.7M	-$794.5M	-267.4M
Cash From Financing Activities	2.603M	$936.6M	-17.58M
Net Change In Cash	-116.0M	$103.1M	-316.2M
YoY Change	-63.32%	-561.23%	-1108.48%
FREE CASH FLOW
Cash From Operating Activities	-$7.908M	-$38.48M	-$31.15M
Capital Expenditures	-$6.729M	$34.82M	-$7.170M
Free Cash Flow	-$1.179M	-$73.30M	-$23.98M
YoY Change	-95.08%	48.12%	-959.5%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2021	dei	Icfr Auditor Attestation Flag IcfrAuditorAttestationFlag	true
CY2021	dei	Entity Shell Company EntityShellCompany	false
CY2021	dei	Entity Central Index Key EntityCentralIndexKey	0001517413
CY2021	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2021
CY2021	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	FY
CY2021	dei	Amendment Flag AmendmentFlag	false
CY2021	dei	Document Type DocumentType	10-K
CY2021	dei	Document Annual Report DocumentAnnualReport	true
CY2021	dei	Document Period End Date DocumentPeriodEndDate	2021-12-31
CY2021	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2021	dei	Document Transition Report DocumentTransitionReport	false
CY2021	dei	Entity File Number EntityFileNumber	001-38897
CY2021	dei	Entity Registrant Name EntityRegistrantName	FASTLY, INC.
CY2021	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	DE
CY2021	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	27-5411834
CY2021	dei	Entity Address Address Line1 EntityAddressAddressLine1	475 Brannan Street, Suite 300
CY2021	dei	Entity Address City Or Town EntityAddressCityOrTown	San Francisco
CY2021	dei	Entity Address State Or Province EntityAddressStateOrProvince	CA
CY2021	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	94107
CY2021	dei	City Area Code CityAreaCode	844
CY2021	dei	Local Phone Number LocalPhoneNumber	432-7859
CY2021	dei	Security12b Title Security12bTitle	Class A Common Stock, $0.00002 par value
CY2021	dei	Trading Symbol TradingSymbol	FSLY
CY2021	dei	Security Exchange Name SecurityExchangeName	NYSE
CY2021	dei	Entity Well Known Seasoned Issuer EntityWellKnownSeasonedIssuer	Yes
CY2021	dei	Entity Voluntary Filers EntityVoluntaryFilers	No
CY2021	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
CY2021	dei	Entity Interactive Data Current EntityInteractiveDataCurrent	Yes
CY2021	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
CY2021	dei	Entity Small Business EntitySmallBusiness	false
CY2021	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
CY2021Q2	dei	Entity Public Float EntityPublicFloat	5600000000	USD
CY2022Q1	dei	Entity Common Stock Shares Outstanding EntityCommonStockSharesOutstanding	120300000	shares
CY2021	dei	Auditor Firm AuditorFirmId	34
CY2021	dei	Auditor Name AuditorName	Deloitte & Touche LLP
CY2021	dei	Auditor Location AuditorLocation	San Francisco, California
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CY2020Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	62900000	USD
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CY2020Q4	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	50258000	USD
CY2021Q4	us-gaap	Restricted Cash And Cash Equivalents At Carrying Value RestrictedCashAndCashEquivalentsAtCarryingValue	0	USD
CY2020Q4	us-gaap	Restricted Cash And Cash Equivalents At Carrying Value RestrictedCashAndCashEquivalentsAtCarryingValue	87000	USD
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CY2020Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	60019000	USD
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CY2021Q4	us-gaap	Available For Sale Securities Debt Securities Noncurrent AvailableForSaleSecuritiesDebtSecuritiesNoncurrent	528911000	USD
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CY2020Q4	us-gaap	Accrued Liabilities Current AccruedLiabilitiesCurrent	34334000	USD
CY2021Q4	us-gaap	Finance Lease Liability Current FinanceLeaseLiabilityCurrent	21125000	USD
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CY2020Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	0	USD
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CY2021Q4	us-gaap	Liabilities Liabilities	1145067000	USD
CY2020Q4	us-gaap	Liabilities Liabilities	158086000	USD
CY2021Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		USD
CY2020Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		USD
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CY2021	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-2633000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-190000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	232000	USD
CY2021	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	-225330000	USD
CY2020Q4	us-gaap	Temporary Equity Shares Issued TemporaryEquitySharesIssued	0	shares
CY2020	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	-96122000	USD
CY2019	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	-51318000	USD
CY2018Q4	us-gaap	Stockholders Equity StockholdersEquity	-131927000	USD
CY2019	fsly	Adjustments To Additional Paid In Capital Conversion Of Preferred Stock Warrants AdjustmentsToAdditionalPaidInCapitalConversionOfPreferredStockWarrants	5665000	USD
CY2019	us-gaap	Stock Issued During Period Value New Issues StockIssuedDuringPeriodValueNewIssues	186912000	USD
CY2019	us-gaap	Stock Issued During Period Value Stock Options Exercised StockIssuedDuringPeriodValueStockOptionsExercised	5579000	USD
CY2019	fsly	Stock Issued During Period Value Vesting Of Early Exercised Stock Options StockIssuedDuringPeriodValueVestingOfEarlyExercisedStockOptions	620000	USD
CY2019	us-gaap	Stock Issued During Period Value Employee Stock Purchase Plan StockIssuedDuringPeriodValueEmployeeStockPurchasePlan	4150000	USD
CY2019	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	12586000	USD
CY2019	fsly	Stockholders Equity Note Repayment StockholdersEquityNoteRepayment	74000	USD
CY2019	us-gaap	Treasury Stock Retired Cost Method Amount TreasuryStockRetiredCostMethodAmount	0	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	-51550000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	232000	USD
CY2019Q4	us-gaap	Stockholders Equity StockholdersEquity	257652000	USD
CY2020	us-gaap	Stock Issued During Period Value New Issues StockIssuedDuringPeriodValueNewIssues	274177000	USD
CY2020	us-gaap	Stock Issued During Period Value Acquisitions StockIssuedDuringPeriodValueAcquisitions	622595000	USD
CY2020	fsly	Stock Awards Acquired During Period Value StockAwardsAcquiredDuringPeriodValue	1129000	USD
CY2020	fsly	Stock Issued During Period Value Acquisition Shares Held Back For Restricted Stock Awards StockIssuedDuringPeriodValueAcquisitionSharesHeldBackForRestrictedStockAwards	87714000	USD
CY2020	us-gaap	Stock Issued During Period Shares Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures	112062	shares
CY2020	us-gaap	Stock Issued During Period Value Stock Options Exercised StockIssuedDuringPeriodValueStockOptionsExercised	15273000	USD
CY2020	fsly	Stock Issued During Period Value Vesting Of Early Exercised Stock Options StockIssuedDuringPeriodValueVestingOfEarlyExercisedStockOptions	467000	USD
CY2020	us-gaap	Stock Issued During Period Value Employee Stock Purchase Plan StockIssuedDuringPeriodValueEmployeeStockPurchasePlan	8193000	USD
CY2020	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	66467000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	-95932000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-190000	USD
CY2020Q4	us-gaap	Stockholders Equity StockholdersEquity	1061865000	USD
CY2020Q4	us-gaap	Stockholders Equity StockholdersEquity	1061865000	USD
CY2021	us-gaap	Stock Issued During Period Value Stock Options Exercised StockIssuedDuringPeriodValueStockOptionsExercised	12626000	USD
CY2021	fsly	Stock Issued During Period Value Vesting Of Early Exercised Stock Options StockIssuedDuringPeriodValueVestingOfEarlyExercisedStockOptions	405000	USD
CY2021	fsly	Stock Sold During Period Value Restricted Stock Award StockSoldDuringPeriodValueRestrictedStockAward	10655000	USD
CY2021	us-gaap	Stock Issued During Period Value Employee Stock Purchase Plan StockIssuedDuringPeriodValueEmployeeStockPurchasePlan	8798000	USD
CY2021	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	144934000	USD
CY2021	us-gaap	Net Income Loss NetIncomeLoss	-222697000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-2633000	USD
CY2021Q4	us-gaap	Stockholders Equity StockholdersEquity	1013953000	USD
CY2021	us-gaap	Net Income Loss NetIncomeLoss	-222697000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	-95932000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	-51550000	USD
CY2021	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	28799000	USD
CY2020	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	19979000	USD
CY2019	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	16553000	USD
CY2021	fsly	Amortization Of Intangible Assets Acquired AmortizationOfIntangibleAssetsAcquired	21238000	USD
CY2020	fsly	Amortization Of Intangible Assets Acquired AmortizationOfIntangibleAssetsAcquired	5078000	USD
CY2019	fsly	Amortization Of Intangible Assets Acquired AmortizationOfIntangibleAssetsAcquired	0	USD
CY2021	fsly	Amortization Of Right Of Use Assets And Other AmortizationOfRightOfUseAssetsAndOther	26883000	USD
CY2020	fsly	Amortization Of Right Of Use Assets And Other AmortizationOfRightOfUseAssetsAndOther	21765000	USD
CY2019	fsly	Amortization Of Right Of Use Assets And Other AmortizationOfRightOfUseAssetsAndOther	0	USD
CY2021	fsly	Amortization Of Deferred Rent AmortizationOfDeferredRent	0	USD
CY2019	us-gaap	Increase Decrease In Prepaid Deferred Expense And Other Assets IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	2666000	USD
CY2021	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	10423000	USD
CY2020	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	17162000	USD
CY2019	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	3945000	USD
CY2020	fsly	Amortization Of Deferred Rent AmortizationOfDeferredRent	0	USD
CY2019	fsly	Amortization Of Deferred Rent AmortizationOfDeferredRent	-711000	USD
CY2021	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	3185000	USD
CY2020	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	219000	USD
CY2019	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	1909000	USD
CY2021	us-gaap	Capitalized Contract Cost Amortization CapitalizedContractCostAmortization	6294000	USD
CY2020	us-gaap	Capitalized Contract Cost Amortization CapitalizedContractCostAmortization	3516000	USD
CY2019	us-gaap	Capitalized Contract Cost Amortization CapitalizedContractCostAmortization	2294000	USD
CY2021	us-gaap	Share Based Compensation ShareBasedCompensation	140488000	USD
CY2020	us-gaap	Share Based Compensation ShareBasedCompensation	64433000	USD
CY2019	us-gaap	Share Based Compensation ShareBasedCompensation	12145000	USD
CY2021	us-gaap	Provision For Doubtful Accounts ProvisionForDoubtfulAccounts	196000	USD
CY2020	us-gaap	Provision For Doubtful Accounts ProvisionForDoubtfulAccounts	1719000	USD
CY2019	us-gaap	Provision For Doubtful Accounts ProvisionForDoubtfulAccounts	360000	USD
CY2021	us-gaap	Fair Value Adjustment Of Warrants FairValueAdjustmentOfWarrants	0	USD
CY2020	us-gaap	Fair Value Adjustment Of Warrants FairValueAdjustmentOfWarrants	0	USD
CY2019	us-gaap	Fair Value Adjustment Of Warrants FairValueAdjustmentOfWarrants	2404000	USD
CY2021	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	-2225000	USD
CY2020	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	-624000	USD
CY2019	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	591000	USD
CY2021	fsly	Interest Paid On Capital Lease InterestPaidOnCapitalLease	1754000	USD
CY2020	fsly	Interest Paid On Capital Lease InterestPaidOnCapitalLease	688000	USD
CY2019	fsly	Interest Paid On Capital Lease InterestPaidOnCapitalLease	364000	USD
CY2021	us-gaap	Gain Loss On Sale Of Property Plant Equipment GainLossOnSaleOfPropertyPlantEquipment	300000	USD
CY2020	us-gaap	Gain Loss On Sale Of Property Plant Equipment GainLossOnSaleOfPropertyPlantEquipment	-653000	USD
CY2019	us-gaap	Gain Loss On Sale Of Property Plant Equipment GainLossOnSaleOfPropertyPlantEquipment	-108000	USD
CY2021	fsly	Tax Benefit Related To Release Of Valuation Allowance TaxBenefitRelatedToReleaseOfValuationAllowance	0	USD
CY2020	fsly	Tax Benefit Related To Release Of Valuation Allowance TaxBenefitRelatedToReleaseOfValuationAllowance	12950000	USD
CY2019	fsly	Tax Benefit Related To Release Of Valuation Allowance TaxBenefitRelatedToReleaseOfValuationAllowance	0	USD
CY2021	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	14563000	USD
CY2020	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	9264000	USD
CY2019	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	12767000	USD
CY2021	us-gaap	Increase Decrease In Prepaid Deferred Expense And Other Assets IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	4777000	USD
CY2020	us-gaap	Increase Decrease In Prepaid Deferred Expense And Other Assets IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	5550000	USD
CY2021	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	146000	USD
CY2020	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	4059000	USD
CY2019	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	2391000	USD
CY2021	us-gaap	Increase Decrease In Accrued Liabilities IncreaseDecreaseInAccruedLiabilities	4261000	USD
CY2020	us-gaap	Increase Decrease In Accrued Liabilities IncreaseDecreaseInAccruedLiabilities	12992000	USD
CY2019	us-gaap	Increase Decrease In Accrued Liabilities IncreaseDecreaseInAccruedLiabilities	4401000	USD
CY2021	fsly	Increase Decrease In Operating Lease Liabilities IncreaseDecreaseInOperatingLeaseLiabilities	-26447000	USD
CY2020	fsly	Increase Decrease In Operating Lease Liabilities IncreaseDecreaseInOperatingLeaseLiabilities	-18264000	USD
CY2019	fsly	Increase Decrease In Operating Lease Liabilities IncreaseDecreaseInOperatingLeaseLiabilities	0	USD
CY2021	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	8764000	USD
CY2020	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	4857000	USD
CY2019	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-1274000	USD
CY2021	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	-38482000	USD
CY2020	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	-19916000	USD
CY2019	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	-31303000	USD
CY2021	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	928155000	USD
CY2020	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	269059000	USD
CY2019	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	190980000	USD
CY2021	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	66527000	USD
CY2020	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	143241000	USD
CY2019	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	52589000	USD
CY2021	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	118085000	USD
CY2020	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	88719000	USD
CY2019	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	70813000	USD
CY2021	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	1169000	USD
CY2020	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	200988000	USD
CY2019	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	0	USD
CY2021	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	588000	USD
CY2020	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	575000	USD
CY2019	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	0	USD
CY2021	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	34816000	USD
CY2020	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	29569000	USD
CY2019	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	14609000	USD
CY2021	us-gaap	Payments For Software PaymentsForSoftware	13479000	USD
CY2020	us-gaap	Payments For Software PaymentsForSoftware	6131000	USD
CY2019	us-gaap	Payments For Software PaymentsForSoftware	4856000	USD
CY2021	us-gaap	Payments To Acquire Intangible Assets PaymentsToAcquireIntangibleAssets	2092000	USD
CY2020	us-gaap	Payments To Acquire Intangible Assets PaymentsToAcquireIntangibleAssets	1811000	USD
CY2019	us-gaap	Payments To Acquire Intangible Assets PaymentsToAcquireIntangibleAssets	635000	USD
CY2021	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-794511000	USD
CY2020	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-275023000	USD
CY2019	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-87678000	USD
CY2021	us-gaap	Proceeds From Issuance Initial Public Offering ProceedsFromIssuanceInitialPublicOffering	0	USD
CY2020	us-gaap	Proceeds From Issuance Initial Public Offering ProceedsFromIssuanceInitialPublicOffering	0	USD
CY2019	us-gaap	Proceeds From Issuance Initial Public Offering ProceedsFromIssuanceInitialPublicOffering	192510000	USD
CY2021	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	0	USD
CY2020	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	274896000	USD
CY2019	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	0	USD
CY2021	us-gaap	Proceeds From Convertible Debt ProceedsFromConvertibleDebt	930775000	USD
CY2020	us-gaap	Proceeds From Convertible Debt ProceedsFromConvertibleDebt	0	USD
CY2019	us-gaap	Proceeds From Convertible Debt ProceedsFromConvertibleDebt	0	USD
CY2021	us-gaap	Proceeds From Notes Payable ProceedsFromNotesPayable	0	USD
CY2020	us-gaap	Proceeds From Notes Payable ProceedsFromNotesPayable	0	USD
CY2019	us-gaap	Proceeds From Notes Payable ProceedsFromNotesPayable	20300000	USD
CY2021	us-gaap	Payments Of Debt Issuance Costs PaymentsOfDebtIssuanceCosts	1351000	USD
CY2020	us-gaap	Payments Of Debt Issuance Costs PaymentsOfDebtIssuanceCosts	0	USD
CY2019	us-gaap	Payments Of Debt Issuance Costs PaymentsOfDebtIssuanceCosts	231000	USD
CY2021	us-gaap	Repayments Of Notes Payable RepaymentsOfNotesPayable	0	USD
CY2020	us-gaap	Repayments Of Notes Payable RepaymentsOfNotesPayable	20300000	USD
CY2019	us-gaap	Repayments Of Notes Payable RepaymentsOfNotesPayable	49167000	USD
CY2021	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	13568000	USD
CY2020	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	5773000	USD
CY2019	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	1370000	USD
CY2021	us-gaap	Proceeds From Stock Plans ProceedsFromStockPlans	8069000	USD
CY2020	us-gaap	Proceeds From Stock Plans ProceedsFromStockPlans	9318000	USD
CY2019	us-gaap	Proceeds From Stock Plans ProceedsFromStockPlans	5402000	USD
CY2021	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	12626000	USD
CY2020	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	15273000	USD
CY2019	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	5579000	USD
CY2021	fsly	Proceeds From Stock Options Exercised Early ProceedsFromStockOptionsExercisedEarly	0	USD
CY2020	fsly	Proceeds From Stock Options Exercised Early ProceedsFromStockOptionsExercisedEarly	0	USD
CY2019	fsly	Proceeds From Stock Options Exercised Early ProceedsFromStockOptionsExercisedEarly	520000	USD
CY2021	fsly	Proceeds From Repayment Of Stockholders Note ProceedsFromRepaymentOfStockholdersNote	0	USD
CY2020	fsly	Proceeds From Repayment Of Stockholders Note ProceedsFromRepaymentOfStockholdersNote	0	USD
CY2019	fsly	Proceeds From Repayment Of Stockholders Note ProceedsFromRepaymentOfStockholdersNote	74000	USD
CY2021	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	936551000	USD
CY2020	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	272739000	USD
CY2019	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	168148000	USD
CY2021	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	-477000	USD
CY2020	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	-149000	USD
CY2019	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	99000	USD
CY2021	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	103081000	USD
CY2020	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-22349000	USD
CY2019	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	49266000	USD
CY2020	fsly	Vesting Of Early Exercised Stock Options VestingOfEarlyExercisedStockOptions	467000	USD
CY2020Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	63880000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	86229000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	36963000	USD
CY2021Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	166961000	USD
CY2020Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	63880000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	86229000	USD
CY2021	us-gaap	Interest Paid Net InterestPaidNet	1938000	USD
CY2020	us-gaap	Interest Paid Net InterestPaidNet	1590000	USD
CY2019	us-gaap	Interest Paid Net InterestPaidNet	5422000	USD
CY2021	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	267000	USD
CY2020	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	1219000	USD
CY2019	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	361000	USD
CY2021	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	18275000	USD
CY2020	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	3184000	USD
CY2019	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	7071000	USD
CY2021	fsly	Vesting Of Early Exercised Stock Options VestingOfEarlyExercisedStockOptions	405000	USD
CY2019	fsly	Vesting Of Early Exercised Stock Options VestingOfEarlyExercisedStockOptions	620000	USD
CY2021	us-gaap	Capital Lease Obligations Incurred CapitalLeaseObligationsIncurred	0	USD
CY2020	us-gaap	Capital Lease Obligations Incurred CapitalLeaseObligationsIncurred	0	USD
CY2019	us-gaap	Capital Lease Obligations Incurred CapitalLeaseObligationsIncurred	7380000	USD
CY2021	fsly	Change In Other Assets From Change In Accounting Principle ChangeInOtherAssetsFromChangeInAccountingPrinciple	0	USD
CY2020	fsly	Change In Other Assets From Change In Accounting Principle ChangeInOtherAssetsFromChangeInAccountingPrinciple	0	USD
CY2019	fsly	Change In Other Assets From Change In Accounting Principle ChangeInOtherAssetsFromChangeInAccountingPrinciple	5727000	USD
CY2021	us-gaap	Conversion Of Stock Amount Converted1 ConversionOfStockAmountConverted1	0	USD
CY2020	us-gaap	Conversion Of Stock Amount Converted1 ConversionOfStockAmountConverted1	0	USD
CY2019	us-gaap	Conversion Of Stock Amount Converted1 ConversionOfStockAmountConverted1	5665000	USD
CY2021	fsly	Cashless Exercise Of Common Stock Warrants CashlessExerciseOfCommonStockWarrants	0	USD
CY2020	fsly	Cashless Exercise Of Common Stock Warrants CashlessExerciseOfCommonStockWarrants	1557000	USD
CY2019	fsly	Cashless Exercise Of Common Stock Warrants CashlessExerciseOfCommonStockWarrants	1036000	USD
CY2021	fsly	Initial Public Offering Costs Incurred But Not Yet Paid InitialPublicOfferingCostsIncurredButNotYetPaid	0	USD
CY2020	fsly	Initial Public Offering Costs Incurred But Not Yet Paid InitialPublicOfferingCostsIncurredButNotYetPaid	0	USD
CY2019	fsly	Initial Public Offering Costs Incurred But Not Yet Paid InitialPublicOfferingCostsIncurredButNotYetPaid	130000	USD
CY2021	us-gaap	Employee Service Share Based Compensation Allocation Of Recognized Period Costs Capitalized Amount EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount	4446000	USD
CY2020	us-gaap	Employee Service Share Based Compensation Allocation Of Recognized Period Costs Capitalized Amount EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount	2034000	USD
CY2019	us-gaap	Employee Service Share Based Compensation Allocation Of Recognized Period Costs Capitalized Amount EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount	441000	USD
CY2021	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	32458000	USD
CY2020	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	23827000	USD
CY2019	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	0	USD
CY2021	us-gaap	Right Of Use Asset Obtained In Exchange For Finance Lease Liability RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability	31529000	USD
CY2020	us-gaap	Right Of Use Asset Obtained In Exchange For Finance Lease Liability RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability	22541000	USD
CY2019	us-gaap	Right Of Use Asset Obtained In Exchange For Finance Lease Liability RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability	0	USD
CY2021	us-gaap	Stock Issued1 StockIssued1	0	USD
CY2020	us-gaap	Stock Issued1 StockIssued1	536432000	USD
CY2019	us-gaap	Stock Issued1 StockIssued1	0	USD
CY2021	fsly	Receivable Related To Shares Of Restricted Stock ReceivableRelatedToSharesOfRestrictedStock	10655000	USD
CY2020	fsly	Receivable Related To Shares Of Restricted Stock ReceivableRelatedToSharesOfRestrictedStock	0	USD
CY2019	fsly	Receivable Related To Shares Of Restricted Stock ReceivableRelatedToSharesOfRestrictedStock	0	USD
CY2021Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	166068000	USD
CY2020Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	62900000	USD
CY2021	us-gaap	Capitalized Contract Cost Amortization CapitalizedContractCostAmortization	6300000	USD
CY2019Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	16142000	USD
CY2021Q4	us-gaap	Restricted Cash Current RestrictedCashCurrent	0	USD
CY2020Q4	us-gaap	Restricted Cash Current RestrictedCashCurrent	87000	USD
CY2019Q4	us-gaap	Restricted Cash Current RestrictedCashCurrent	70087000	USD
CY2021Q4	us-gaap	Restricted Cash Equivalents RestrictedCashEquivalents	893000	USD
CY2020Q4	us-gaap	Restricted Cash Equivalents RestrictedCashEquivalents	893000	USD
CY2019Q4	us-gaap	Restricted Cash Equivalents RestrictedCashEquivalents	0	USD
CY2021Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	166961000	USD
CY2020Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	63880000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	86229000	USD
CY2021	us-gaap	Nature Of Operations NatureOfOperations	Nature of Business<div style="margin-bottom:12pt;text-indent:27pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Fastly, Inc. has built an edge cloud platform that can process, serve, and secure its customer’s applications as close to their end users as possible. As of December 31, 2021, our edge network spans across 71 markets. We were incorporated in Delaware in 2011 and are headquartered in San Francisco, California.</span></div><div style="margin-bottom:12pt;text-indent:27pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">As used herein, "Fastly," "we," "our," "the Company," and similar terms include Fastly, Inc. and its subsidiaries, unless the context indicates otherwise.</span></div><div style="margin-bottom:12pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:700;line-height:120%">Initial Public Offering ("IPO")</span></div><div style="margin-bottom:12pt;text-indent:27pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">On May 21, 2019 we completed an IPO in which we sold 12,937,500 shares of our newly authorized Class A common stock, which included 1,687,500 shares sold pursuant to the exercise by the underwriters of an option to purchase additional shares, at the public offering price of $16.00 per share. We received net proceeds of $192.5 million, after deducting underwriting discounts and commissions, from sales of our shares in the IPO. The net proceeds include additional proceeds of $25.1 million, net of underwriters' discounts and commissions, from the exercise of the underwriters' option to purchase an additional 1,687,500 shares of our Class A common stock. Prior to the closing of the IPO, all shares of common stock then outstanding were reclassified as Class B common stock. </span></div><div style="margin-bottom:12pt;text-indent:27pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Immediately upon the closing of the IPO, all shares of convertible preferred stock then outstanding were converted into 53,630,213 shares of Class B common stock on a one-to-one basis. Prior to the IPO, we had seven outstanding series of convertible preferred stock each with a par value of $0.00002 per share, convertible at the option of the holder, that was classified as temporary equity on our consolidated balance sheet. On May 17, 2019, immediately upon closing of the IPO, our convertible preferred stock was automatically converted to shares of our Class B common stock. As of both December 31, 2021 and 2020, we had zero convertible preferred stock issued or outstanding.</span></div><div style="margin-bottom:12pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:700;line-height:120%">Follow-on Public Offering</span></div><div style="margin-bottom:12pt;text-indent:27pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">On May 26, 2020, we completed a follow-on public offering in which we sold 6,900,000 shares of Class A common stock, which included 900,000 shares sold pursuant to the exercise by the underwriters of an option to purchase additional shares, at the public offering price of $41.50 per share. We received net proceeds of $274.9 million, after deducting underwriting discounts and commissions, from sales of our shares in the public offering.</span></div><div style="margin-bottom:12pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:700;line-height:120%">Conversion of Dual Class Common Stock Structure</span></div><div style="margin-bottom:12pt;text-indent:27pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">On October 12, 2020, the outstanding shares of our Class B common stock represented less than 10% of the aggregate number of shares of the then outstanding Class A common stock and Class B common stock. As a result, all our outstanding shares of Class B common stock automatically converted into the same number of shares of Class A common stock on July 12, 2021, pursuant to the terms of our amended and restated certificate of incorporation (the "Certificate"). Upon the conversion outstanding options denominated in shares of Class B common stock issued under any of our equity incentive plans remained unchanged, except that they now represent the right to receive shares of Class A common stock. In accordance with the Certificate, the shares of Class B common stock that converted to Class A common stock were retired and will not be reissued by us.</span></div>
CY2021Q4	fsly	Operating Markets OperatingMarkets	71	operatingMarket
CY2019Q2	fsly	Convertible Preferred Stock Number Of Series ConvertiblePreferredStockNumberOfSeries	7	stockSeries
CY2019Q2	us-gaap	Temporary Equity Par Or Stated Value Per Share TemporaryEquityParOrStatedValuePerShare	0.00002
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CY2021Q4	us-gaap	Temporary Equity Shares Outstanding TemporaryEquitySharesOutstanding	0	shares
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CY2021	us-gaap	Use Of Estimates UseOfEstimates	<div style="margin-bottom:12pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:700;line-height:120%">Use of Estimates</span></div><div style="text-indent:27pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:112%">The preparation of our consolidated financial statements requires us to make estimates, judgments, and assumptions that affect the reported amounts of assets, liabilities, revenue, costs and expenses, and related disclosures. Actual results and outcomes could differ significantly from our estimates, judgments, and assumptions. Significant estimates, judgments, and assumptions used in these financial statements include, but are not limited to, those related to revenue, accounts receivable and related reserves, fair value of assets acquired and liabilities assumed for business combinations, useful lives and realizability of long-lived assets including our goodwill and intangible assets, income tax reserves, and accounting for stock-based compensation. Estimates are periodically reviewed in light of changes in circumstances, facts, and experience. The effects of material revisions in estimates are reflected in the consolidated financial statements in the period of change and prospectively from the date of the change in estimate.</span></div><div style="text-indent:27pt"><span><br/></span></div><div style="margin-bottom:12pt;text-indent:27pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">The ongoing global COVID-19 pandemic has adversely impacted many operational aspects of our business and may continue to do so in the future. Since the start of the global pandemic, we have assessed the impact that COVID-19 had on our results of operations, including, but not limited to an assessment of our allowance for credit losses, the carrying value of short-term and long-term marketable securities, the carrying value of goodwill and other long-lived assets, and the impact to revenue recognition and cost of revenues. The future impacts of the pandemic and any resulting economic impact are largely unknown and continuing to evolve. We will continue to actively monitor the impact that COVID-19 has on the results of our business operations, and may make decisions required by federal, state or local authorities, or that are determined to be in the best interests of our employees, customers, partners, suppliers and stockholders. As a result, our estimates and judgments may change materially as new events occur or additional information becomes available to us.</span></div>
CY2021Q4	us-gaap	Restricted Cash RestrictedCash	900000	USD
CY2020Q4	us-gaap	Restricted Cash RestrictedCash	1000000	USD
CY2020Q4	us-gaap	Restricted Cash Equivalents RestrictedCashEquivalents	900000	USD
CY2021Q4	us-gaap	Restricted Cash Equivalents RestrictedCashEquivalents	900000	USD
CY2020	us-gaap	Capitalized Contract Cost Amortization CapitalizedContractCostAmortization	3500000	USD
CY2021	us-gaap	Concentration Risk Credit Risk ConcentrationRiskCreditRisk	<div style="margin-bottom:12pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:700;line-height:120%">Concentrations of Credit Risk</span></div><div style="margin-bottom:12pt;text-indent:27pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Financial instruments that potentially subject us to significant concentration of credit risk consist primarily of cash, cash equivalents, marketable securities, and accounts receivable. The primary focus of our investment strategy is to preserve capital and meet liquidity requirements. Our investment policy addresses the level of credit exposure by limiting the concentration in any one corporate issuer or sector and establishing a minimum allowable credit rating. To manage the risk exposure, we invest cash equivalents and marketable securities in a variety of fixed income securities, including government and investment-grade debt securities and money market funds. We place our cash primarily in checking and money market accounts with reputable financial institutions. Deposits held with these financial institutions may exceed the amount of insurance provided on such deposits, if any.</span></div>Concentrations of credit risk with respect to accounts receivable are primarily limited to certain customers from which we generate significant revenue. Our customer base consists of a large number of geographically dispersed customers diversified across several industries. To reduce this risk, we routinely assess the financial strength of our customers. Based on such assessments, we believe that our accounts receivable credit risk exposure is limited.
CY2019	us-gaap	Advertising Expense AdvertisingExpense	1400000	USD
CY2021	us-gaap	Advertising Expense AdvertisingExpense	2300000	USD
CY2020	us-gaap	Advertising Expense AdvertisingExpense	3800000	USD
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CY2020Q1	us-gaap	Operating Lease Liability OperatingLeaseLiability	56300000	USD
CY2021	us-gaap	Revenue From Contract With Customer Including Assessed Tax RevenueFromContractWithCustomerIncludingAssessedTax	354330000	USD
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CY2021Q4	fsly	Enterprise Customer Threshold EnterpriseCustomerThreshold	100000	USD
CY2021	us-gaap	Revenue From Contract With Customer Including Assessed Tax RevenueFromContractWithCustomerIncludingAssessedTax	354330000	USD
CY2020	us-gaap	Revenue From Contract With Customer Including Assessed Tax RevenueFromContractWithCustomerIncludingAssessedTax	290874000	USD
CY2019	us-gaap	Revenue From Contract With Customer Including Assessed Tax RevenueFromContractWithCustomerIncludingAssessedTax	200462000	USD
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CY2020Q4	us-gaap	Contract With Customer Asset Net ContractWithCustomerAssetNet	387000	USD
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CY2020Q4	us-gaap	Contract With Customer Liability ContractWithCustomerLiability	18020000	USD
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CY2020	us-gaap	Contract With Customer Liability Revenue Recognized ContractWithCustomerLiabilityRevenueRecognized	310000	USD
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CY2020Q4	us-gaap	Available For Sale Securities Debt Securities Noncurrent AvailableForSaleSecuritiesDebtSecuritiesNoncurrent	20448000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	890706000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	151731000	USD
CY2021Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	892948000	USD
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CY2021Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	2243000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	890706000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	151626000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	110000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	5000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	151731000	USD
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CY2020Q4	us-gaap	Assets Fair Value Disclosure AssetsFairValueDisclosure	194338000	USD
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CY2020	us-gaap	Business Acquisitions Pro Forma Revenue BusinessAcquisitionsProFormaRevenue	218529000	USD
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CY2020	us-gaap	Business Acquisitions Pro Forma Net Income Loss BusinessAcquisitionsProFormaNetIncomeLoss	-178124000	USD
CY2020Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	3248000	USD
CY2019Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	1816000	USD
CY2021	us-gaap	Provision For Doubtful Accounts ProvisionForDoubtfulAccounts	196000	USD
CY2020	us-gaap	Provision For Doubtful Accounts ProvisionForDoubtfulAccounts	1719000	USD
CY2021	us-gaap	Allowance For Doubtful Accounts Receivable Write Offs AllowanceForDoubtfulAccountsReceivableWriteOffs	133000	USD
CY2020	us-gaap	Allowance For Doubtful Accounts Receivable Write Offs AllowanceForDoubtfulAccountsReceivableWriteOffs	287000	USD
CY2021Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	3311000	USD
CY2020Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	3248000	USD
CY2021Q4	us-gaap	Property Plant And Equipment And Finance Lease Right Of Use Asset Before Accumulated Depreciation And Amortization PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization	254811000	USD
CY2020Q4	us-gaap	Property Plant And Equipment And Finance Lease Right Of Use Asset Before Accumulated Depreciation And Amortization PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization	157632000	USD
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CY2021Q4	us-gaap	Property Plant And Equipment And Finance Lease Right Of Use Asset After Accumulated Depreciation And Amortization PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization	166961000	USD
CY2020Q4	us-gaap	Property Plant And Equipment And Finance Lease Right Of Use Asset After Accumulated Depreciation And Amortization PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization	95979000	USD
CY2021	us-gaap	Depreciation And Amortization DepreciationAndAmortization	28800000	USD
CY2020	us-gaap	Depreciation And Amortization DepreciationAndAmortization	19800000	USD
CY2019	us-gaap	Depreciation And Amortization DepreciationAndAmortization	16400000	USD
CY2021Q4	us-gaap	Finance Lease Right Of Use Asset Before Accumulated Amortization FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization	67800000	USD
CY2020Q4	us-gaap	Finance Lease Right Of Use Asset Before Accumulated Amortization FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization	36200000	USD
CY2021Q4	us-gaap	Finance Lease Right Of Use Asset Accumulated Amortization FinanceLeaseRightOfUseAssetAccumulatedAmortization	14400000	USD
CY2020Q4	us-gaap	Finance Lease Right Of Use Asset Accumulated Amortization FinanceLeaseRightOfUseAssetAccumulatedAmortization	6700000	USD
CY2021Q4	us-gaap	Employee Related Liabilities Current EmployeeRelatedLiabilitiesCurrent	13543000	USD
CY2020Q4	us-gaap	Employee Related Liabilities Current EmployeeRelatedLiabilitiesCurrent	17840000	USD
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CY2020Q4	fsly	Accrued Colocation And Bandwidth Costs AccruedColocationAndBandwidthCosts	3644000	USD
CY2021Q4	us-gaap	Sales And Excise Tax Payable Current SalesAndExciseTaxPayableCurrent	7498000	USD
CY2020Q4	us-gaap	Sales And Excise Tax Payable Current SalesAndExciseTaxPayableCurrent	6274000	USD
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CY2020Q4	fsly	Accrued Acquisition Related Costs Current AccruedAcquisitionRelatedCostsCurrent	2208000	USD
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CY2020Q4	us-gaap	Other Accrued Liabilities Current OtherAccruedLiabilitiesCurrent	4368000	USD
CY2021Q4	us-gaap	Accrued Liabilities Current AccruedLiabilitiesCurrent	36112000	USD
CY2020Q4	us-gaap	Accrued Liabilities Current AccruedLiabilitiesCurrent	34334000	USD
CY2021Q4	us-gaap	Contract With Customer Liability Current ContractWithCustomerLiabilityCurrent	26421000	USD
CY2020Q4	us-gaap	Contract With Customer Liability Current ContractWithCustomerLiabilityCurrent	15916000	USD
CY2021Q4	fsly	Accrued Computer And Networking Equipment AccruedComputerAndNetworkingEquipment	18081000	USD
CY2020Q4	fsly	Accrued Computer And Networking Equipment AccruedComputerAndNetworkingEquipment	3126000	USD
CY2021Q4	fsly	Liability For Early Exercised Stock Options Current LiabilityForEarlyExercisedStockOptionsCurrent	0	USD
CY2020Q4	fsly	Liability For Early Exercised Stock Options Current LiabilityForEarlyExercisedStockOptionsCurrent	255000	USD
CY2021Q4	us-gaap	Other Sundry Liabilities Current OtherSundryLiabilitiesCurrent	605000	USD
CY2020Q4	us-gaap	Other Sundry Liabilities Current OtherSundryLiabilitiesCurrent	380000	USD
CY2021Q4	us-gaap	Other Liabilities Current OtherLiabilitiesCurrent	45107000	USD
CY2020Q4	us-gaap	Other Liabilities Current OtherLiabilitiesCurrent	19677000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	232000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-190000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-2633000	USD
CY2021	fsly	Subleases Remaining Lease Terms SubleasesRemainingLeaseTerms	P2Y9M
CY2021	us-gaap	Sublease Income SubleaseIncome	1000000	USD
CY2020	us-gaap	Sublease Income SubleaseIncome	1300000	USD
CY2019	us-gaap	Sublease Income SubleaseIncome	1200000	USD
CY2021	us-gaap	Operating Lease Cost OperatingLeaseCost	26716000	USD
CY2020	us-gaap	Operating Lease Cost OperatingLeaseCost	21765000	USD
CY2021	us-gaap	Variable Lease Cost VariableLeaseCost	6820000	USD
CY2020	us-gaap	Variable Lease Cost VariableLeaseCost	4363000	USD
CY2021	fsly	Operating Variable And Short Term Lease Costs OperatingVariableAndShortTermLeaseCosts	33536000	USD
CY2020	fsly	Operating Variable And Short Term Lease Costs OperatingVariableAndShortTermLeaseCosts	26128000	USD
CY2021	us-gaap	Finance Lease Right Of Use Asset Amortization FinanceLeaseRightOfUseAssetAmortization	6834000	USD
CY2020	us-gaap	Finance Lease Right Of Use Asset Amortization FinanceLeaseRightOfUseAssetAmortization	2858000	USD
CY2021	us-gaap	Finance Lease Interest Expense FinanceLeaseInterestExpense	1754000	USD
CY2020	us-gaap	Finance Lease Interest Expense FinanceLeaseInterestExpense	688000	USD
CY2021	fsly	Finance Lease Cost FinanceLeaseCost	8588000	USD
CY2020	fsly	Finance Lease Cost FinanceLeaseCost	3546000	USD
CY2021	us-gaap	Operating Lease Payments OperatingLeasePayments	26447000	USD
CY2020	us-gaap	Operating Lease Payments OperatingLeasePayments	18264000	USD
CY2021	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	13568000	USD
CY2020	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	5773000	USD
CY2021	us-gaap	Finance Lease Interest Payment On Liability FinanceLeaseInterestPaymentOnLiability	1754000	USD
CY2020	us-gaap	Finance Lease Interest Payment On Liability FinanceLeaseInterestPaymentOnLiability	688000	USD
CY2021	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	32458000	USD
CY2020	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	23827000	USD
CY2021	us-gaap	Right Of Use Asset Obtained In Exchange For Finance Lease Liability RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability	31529000	USD
CY2020	us-gaap	Right Of Use Asset Obtained In Exchange For Finance Lease Liability RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability	22541000	USD
CY2021Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P4Y4M28D
CY2020Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P4Y5M8D
CY2021Q4	us-gaap	Finance Lease Weighted Average Remaining Lease Term1 FinanceLeaseWeightedAverageRemainingLeaseTerm1	P2Y2M23D
CY2020Q4	us-gaap	Finance Lease Weighted Average Remaining Lease Term1 FinanceLeaseWeightedAverageRemainingLeaseTerm1	P2Y6M3D
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CY2020Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.0568
CY2021Q4	us-gaap	Finance Lease Weighted Average Discount Rate Percent FinanceLeaseWeightedAverageDiscountRatePercent	0.0486
CY2020Q4	us-gaap	Finance Lease Weighted Average Discount Rate Percent FinanceLeaseWeightedAverageDiscountRatePercent	0.0512
CY2021Q4	fsly	Lessee Operating Lease Lease Not Yet Commenced Commitment Amount LesseeOperatingLeaseLeaseNotYetCommencedCommitmentAmount	5900000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due Next Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths	19389000	USD
CY2021Q4	us-gaap	Finance Lease Liability Payments Due Next Twelve Months FinanceLeaseLiabilityPaymentsDueNextTwelveMonths	22700000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	18297000	USD
CY2021Q4	us-gaap	Finance Lease Liability Payments Due Year Two FinanceLeaseLiabilityPaymentsDueYearTwo	17216000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	15014000	USD
CY2021Q4	us-gaap	Finance Lease Liability Payments Due Year Three FinanceLeaseLiabilityPaymentsDueYearThree	5855000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	13391000	USD
CY2021Q4	us-gaap	Finance Lease Liability Payments Due Year Four FinanceLeaseLiabilityPaymentsDueYearFour	0	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Five LesseeOperatingLeaseLiabilityPaymentsDueYearFive	13174000	USD
CY2021Q4	us-gaap	Finance Lease Liability Payments Due Year Five FinanceLeaseLiabilityPaymentsDueYearFive	0	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due After Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive	5813000	USD
CY2021Q4	us-gaap	Finance Lease Liability Payments Due After Year Five FinanceLeaseLiabilityPaymentsDueAfterYearFive	0	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	85078000	USD
CY2021Q4	us-gaap	Finance Lease Liability Payments Due FinanceLeaseLiabilityPaymentsDue	45771000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	9693000	USD
CY2021Q4	us-gaap	Finance Lease Liability Undiscounted Excess Amount FinanceLeaseLiabilityUndiscountedExcessAmount	2353000	USD
CY2021Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	75385000	USD
CY2021Q4	us-gaap	Finance Lease Liability FinanceLeaseLiability	43418000	USD
CY2020Q4	us-gaap	Goodwill Goodwill	635590000	USD
CY2019Q4	us-gaap	Goodwill Goodwill	372000	USD
CY2021	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	1169000	USD
CY2020	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	635204000	USD
CY2021	us-gaap	Goodwill Foreign Currency Translation Gain Loss GoodwillForeignCurrencyTranslationGainLoss	46000	USD
CY2020	us-gaap	Goodwill Foreign Currency Translation Gain Loss GoodwillForeignCurrencyTranslationGainLoss	14000	USD
CY2021Q4	us-gaap	Goodwill Goodwill	636805000	USD
CY2020Q4	us-gaap	Goodwill Goodwill	635590000	USD
CY2021	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	1200000	USD
CY2020	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	0	USD
CY2021	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	0	USD
CY2019	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	0	USD
CY2021Q4	us-gaap	Intangible Assets Gross Excluding Goodwill IntangibleAssetsGrossExcludingGoodwill	129491000	USD
CY2021Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	26895000	USD
CY2021Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	102596000	USD
CY2020Q4	us-gaap	Intangible Assets Gross Excluding Goodwill IntangibleAssetsGrossExcludingGoodwill	127398000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	5656000	USD
CY2020Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	121742000	USD
CY2021	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	21200000	USD
CY2020	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	5300000	USD
CY2019	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	100000	USD
CY2021Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Next Twelve Months FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths	20974000	USD
CY2021Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Two FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo	19874000	USD
CY2021Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Three FiniteLivedIntangibleAssetsAmortizationExpenseYearThree	19040000	USD
CY2021Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Four FiniteLivedIntangibleAssetsAmortizationExpenseYearFour	16561000	USD
CY2021Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Five FiniteLivedIntangibleAssetsAmortizationExpenseYearFive	9065000	USD
CY2021Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense After Year Five FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive	16714000	USD
CY2021Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	102228000	USD
CY2020Q4	us-gaap	Line Of Credit LineOfCredit	20300000	USD
CY2020Q4	fsly	Cash Collateral For Line Of Credit CashCollateralForLineOfCredit	70100000	USD
CY2021	us-gaap	Interest Expense Debt InterestExpenseDebt	3500000	USD
CY2020	us-gaap	Interest Expense Debt InterestExpenseDebt	900000	USD
CY2019	us-gaap	Interest Expense Debt InterestExpenseDebt	5200000	USD
CY2021Q4	us-gaap	Debt Instrument Interest Rate Effective Percentage DebtInstrumentInterestRateEffectivePercentage	0.0039
CY2021Q4	us-gaap	Debt Instrument Carrying Amount DebtInstrumentCarryingAmount	948750000	USD
CY2021Q4	us-gaap	Debt Instrument Unamortized Discount DebtInstrumentUnamortizedDiscount	15545000	USD
CY2021Q4	us-gaap	Long Term Debt Current LongTermDebtCurrent	0	USD
CY2021Q4	us-gaap	Long Term Debt LongTermDebt	933205000	USD
CY2021Q4	us-gaap	Purchase Obligation Due In Next Twelve Months PurchaseObligationDueInNextTwelveMonths	49056000	USD
CY2021Q4	us-gaap	Purchase Obligation Due In Second Year PurchaseObligationDueInSecondYear	20147000	USD
CY2021Q4	us-gaap	Purchase Obligation Due In Third Year PurchaseObligationDueInThirdYear	3769000	USD
CY2021Q4	us-gaap	Purchase Obligation Due In Fourth Year PurchaseObligationDueInFourthYear	169000	USD
CY2021Q4	us-gaap	Purchase Obligation Due In Fifth Year PurchaseObligationDueInFifthYear	160000	USD
CY2021Q4	us-gaap	Purchase Obligation Due After Fifth Year PurchaseObligationDueAfterFifthYear	82000	USD
CY2021Q4	us-gaap	Purchase Obligation PurchaseObligation	73383000	USD
CY2021Q4	us-gaap	Sales And Excise Tax Payable Current SalesAndExciseTaxPayableCurrent	7500000	USD
CY2020Q4	us-gaap	Sales And Excise Tax Payable Current SalesAndExciseTaxPayableCurrent	6300000	USD
CY2020Q3	fsly	Loss Contingency Pending Claims Number Consolidated LossContingencyPendingClaimsNumberConsolidated	2	lawsuit
CY2020Q3	us-gaap	Loss Contingency Pending Claims Number LossContingencyPendingClaimsNumber	1	lawsuit
CY2019Q2	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	10000000	shares
CY2019Q2	us-gaap	Preferred Stock Par Or Stated Value Per Share PreferredStockParOrStatedValuePerShare	0.00002
CY2021Q4	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	0	shares
CY2020Q4	us-gaap	Preferred Stock Shares Outstanding PreferredStockSharesOutstanding	0	shares
CY2021Q4	us-gaap	Preferred Stock Shares Outstanding PreferredStockSharesOutstanding	0	shares
CY2020Q4	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	0	shares
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	12210000	shares
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	2.96
CY2018	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	P7Y9M18D
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue	64590000	USD
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	2516000	shares
CY2019	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice	10.87
CY2019	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	2650000	shares
CY2019	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	2.45
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod	807000	shares
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice	5.10
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	11269000	shares
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	4.68
CY2019	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	P7Y3M18D
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue	173471000	USD
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	252000	shares
CY2020	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice	12.96
CY2020	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	4360000	shares
CY2020	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	3.46
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod	198000	shares
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice	8.79
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	6963000	shares
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	5.63
CY2020	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	P6Y8M12D
CY2021	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice	0
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue	569094000	USD
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	0	shares
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	200900000	USD
CY2021	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	2188000	shares
CY2021	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	5.77
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod	406000	shares
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice	11.10
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	4369000	shares
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	5.07
CY2021	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	P5Y1M6D
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue	132721000	USD
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Exercisable Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber	3579000	shares
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Exercisable Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice	4.10
CY2021	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested And Expected To Vest Exercisable Weighted Average Remaining Contractual Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageRemainingContractualTerm1	P4Y8M12D
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Exercisable Aggregate Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue	112280000	USD
CY2021Q4	fsly	Share Based Compensation Arrangement By Share Based Payment Award Options Unvested Exercisable Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsUnvestedExercisableNumber	134000	shares
CY2021Q4	fsly	Share Based Compensation Arrangement By Share Based Payment Award Options Unvested Exercisable Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsUnvestedExercisableWeightedAverageExercisePrice	6.70
CY2021	fsly	Share Based Compensation Arrangement By Share Based Payment Award Options Unvested Exercisable Weighted Average Remaining Contractual Term ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsUnvestedExercisableWeightedAverageRemainingContractualTerm	P6Y10M24D
CY2021Q4	fsly	Share Based Compensation Arrangement By Share Based Payment Award Options Unvested Exercisable Aggregate Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsUnvestedExercisableAggregateIntrinsicValue	3834000	USD
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	64900000	USD
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	32600000	USD
CY2021	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested In Period Fair Value1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1	6900000	USD
CY2020	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested In Period Fair Value1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1	10300000	USD
CY2019	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested In Period Fair Value1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1	6100000	USD
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	0.00
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	86.77
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	5.77
CY2021Q4	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Stock Options EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions	9400000	USD
CY2020Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Number Of Shares SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares	91000	shares
CY2019Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Number Of Shares SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares	200000	shares
CY2018Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Number Of Shares SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares	245000	shares
CY2021	fsly	Share Based Compensation Arrangement By Share Based Payment Award Options Nonvested Exercised Number Of Shares ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsNonvestedExercisedNumberOfShares	0	shares
CY2020	fsly	Share Based Compensation Arrangement By Share Based Payment Award Options Nonvested Exercised Number Of Shares ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsNonvestedExercisedNumberOfShares	0	shares
CY2021	fsly	Amount Withheld In Contributions For Employee Stock Purchase Plan AmountWithheldInContributionsForEmployeeStockPurchasePlan	8100000	USD
CY2020	fsly	Amount Withheld In Contributions For Employee Stock Purchase Plan AmountWithheldInContributionsForEmployeeStockPurchasePlan	9600000	USD
CY2019	fsly	Share Based Compensation Arrangement By Share Based Payment Award Options Nonvested Exercised Number Of Shares ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsNonvestedExercisedNumberOfShares	117000	shares
CY2021	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested Number Of Shares SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares	91000	shares
CY2020	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested Number Of Shares SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares	109000	shares
CY2019	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested Number Of Shares SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares	162000	shares
CY2021	fsly	Share Based Compensation Arrangement By Share Based Payment Award Options Nonvested Repurchased In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsNonvestedRepurchasedInPeriod	0	shares
CY2020	fsly	Share Based Compensation Arrangement By Share Based Payment Award Options Nonvested Repurchased In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsNonvestedRepurchasedInPeriod	0	shares
CY2019	fsly	Share Based Compensation Arrangement By Share Based Payment Award Options Nonvested Repurchased In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsNonvestedRepurchasedInPeriod	0	shares
CY2021Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Number Of Shares SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares	0	shares
CY2020Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Number Of Shares SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares	91000	shares
CY2019Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Number Of Shares SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares	200000	shares
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue	22.58
CY2021Q1	fsly	Number Of Shares Issued For Each Performance Based Stock Unit NumberOfSharesIssuedForEachPerformanceBasedStockUnit	1
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate	0
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate	0
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate	0
CY2019	fsly	Amount Withheld In Contributions For Employee Stock Purchase Plan AmountWithheldInContributionsForEmployeeStockPurchasePlan	5500000	USD
CY2021	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Period For Recognition1 EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1	P0Y4M24D
CY2021	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	140488000	USD
CY2020	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	64433000	USD
CY2019	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	12145000	USD
CY2021	us-gaap	Employee Service Share Based Compensation Allocation Of Recognized Period Costs Capitalized Amount EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount	4400000	USD
CY2020	us-gaap	Employee Service Share Based Compensation Allocation Of Recognized Period Costs Capitalized Amount EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount	2000000	USD
CY2019	us-gaap	Employee Service Share Based Compensation Allocation Of Recognized Period Costs Capitalized Amount EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount	400000	USD
CY2021	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	19341000	shares
CY2020	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	12471000	shares
CY2019	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	13540000	shares
CY2021	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	-224159000	USD
CY2020	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	-86842000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	-30970000	USD
CY2021	us-gaap	Income Loss From Continuing Operations Before Income Taxes Foreign IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign	1531000	USD
CY2020	us-gaap	Income Loss From Continuing Operations Before Income Taxes Foreign IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign	-20570000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Foreign IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign	-20088000	USD
CY2021	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	-222628000	USD
CY2020	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	-107412000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	-51058000	USD
CY2021	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	0	USD
CY2020	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	0	USD
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CY2021	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	322000	USD
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CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	492000	USD
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CY2021	fsly	Effective Income Tax Rate Reconciliation Acquisition Related Expenses Percent EffectiveIncomeTaxRateReconciliationAcquisitionRelatedExpensesPercent	0
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CY2021	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0
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CY2021	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	100000	USD
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CY2020Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	3186000	USD
CY2021Q4	us-gaap	Unrecognized Tax Benefits That Would Impact Effective Tax Rate UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate	7800000	USD
CY2020Q4	us-gaap	Unrecognized Tax Benefits That Would Impact Effective Tax Rate UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate	3000000	USD
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CY2020Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	95979000	USD

Files In Submission

Name	View Source	Status
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0001517413-22-000038-index.html	Edgar Link	pending
0001517413-22-000038.txt	Edgar Link	pending
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fastly-10xkxdescriptionofs.htm	Edgar Link	pending
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Financial_Report.xlsx	Edgar Link	pending
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MetaLinks.json	Edgar Link	pending
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R98.htm	Edgar Link	pending
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report.css	Edgar Link	pending
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$FSLY
Fastly, Inc. Stock $fsly

2021 Q4 Form 10-K Financial Statement

#000151741322000038 Filed on March 01, 2022

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$FSLY Fastly, Inc. Stock $fsly

2021 Q4 Form 10-K Financial Statement

#000151741322000038 Filed on March 01, 2022

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$FSLY
Fastly, Inc. Stock $fsly