$FSLY
Fastly Inc Stock $fsly

$fsly Overview Financials Valuation SEC Filings Company Website

2019 Q4 Form 10-K Financial Statement

#000151741320000043 Filed on March 04, 2020

Income Statement

Concept	2019 Q4	2018 Q4	2017 Q4
Revenue	$58.94M	$40.80M	$30.04M
YoY Change	44.46%	35.82%
Cost Of Revenue	$25.53M	$17.71M	$14.49M
YoY Change	44.16%	22.22%
Gross Profit	$33.41M	$23.09M	$15.54M
YoY Change	44.69%	48.58%
Gross Profit Margin	56.68%	56.59%	51.73%
Selling, General & Admin	$34.49M	$20.84M	$16.73M
YoY Change	65.5%	24.57%
% of Gross Profit	103.23%	90.26%	107.66%
Research & Development	$12.95M	$9.310M	$7.910M
YoY Change	39.1%	17.7%
% of Gross Profit	38.76%	40.32%	50.9%
Depreciation & Amortization	$4.860M	$3.680M
YoY Change	32.07%
% of Gross Profit	14.55%	15.94%
Operating Expenses	$47.44M	$30.15M	$24.64M
YoY Change	57.35%	22.36%
Operating Profit	-$14.03M	-$7.060M	-$9.100M
YoY Change	98.73%	-22.42%
Interest Expense	$470.0K	-$230.0K	-$200.0K
YoY Change	-304.35%	15.0%
% of Operating Profit
Other Income/Expense, Net	-$200.0K	$20.00K	-$70.00K
YoY Change	-1100.0%	-128.57%
Pretax Income	-$13.76M	-$7.270M	-$9.360M
YoY Change	89.27%	-22.33%
Income Tax	$310.0K	$40.00K	$60.00K
% Of Pretax Income
Net Earnings	-$14.07M	-$7.310M	-$9.410M
YoY Change	92.48%	-22.32%
Net Earnings / Revenue	-23.87%	-17.92%	-31.32%
Basic Earnings Per Share
Diluted Earnings Per Share	-$149.1K	-$80.60K	-$103.8K
COMMON SHARES
Basic Shares Outstanding
Diluted Shares Outstanding

Balance Sheet

Concept	2019 Q4	2018 Q4	2017 Q4
SHORT-TERM ASSETS
Cash & Short-Term Investments	$131.1M	$83.64M
YoY Change	56.75%
Cash & Equivalents	$16.14M	$36.96M	$31.31M
Short-Term Investments	$115.0M	$46.68M
Other Short-Term Assets	$81.10M
YoY Change
Inventory
Prepaid Expenses
Receivables	$37.14M	$24.73M
Other Receivables	$0.00
Total Short-Term Assets	$249.3M	$117.3M
YoY Change	112.61%
LONG-TERM ASSETS
Property, Plant & Equipment	$60.04M	$42.35M
YoY Change	41.75%
Goodwill	$372.0K	$360.0K	$382.0K
YoY Change	3.33%	-5.76%
Intangibles	$1.125M	$610.0K
YoY Change	84.43%
Long-Term Investments
YoY Change
Other Assets	$10.11M	$2.163M
YoY Change	367.5%
Total Long-Term Assets	$71.65M	$45.49M
YoY Change	57.51%
TOTAL ASSETS
Total Short-Term Assets	$249.3M	$117.3M
Total Long-Term Assets	$71.65M	$45.49M
Total Assets	$321.0M	$162.8M
YoY Change	97.21%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$4.602M	$2.333M
YoY Change	97.26%
Accrued Expenses	$19.88M	$15.54M
YoY Change	27.96%
Deferred Revenue	$317.0K	$1.622M
YoY Change	-80.46%
Short-Term Debt	$0.00
YoY Change
Long-Term Debt Due	$4.472M	$11.37M
YoY Change	-60.67%
Total Short-Term Liabilities	$37.12M	$31.75M
YoY Change	16.92%
LONG-TERM LIABILITIES
Long-Term Debt	$20.08M	$39.44M
YoY Change	-49.08%
Other Long-Term Liabilities	$1.038M	$647.0K
YoY Change	60.43%
Total Long-Term Liabilities	$21.12M	$40.09M
YoY Change	-47.32%
TOTAL LIABILITIES
Total Short-Term Liabilities	$37.12M	$31.75M
Total Long-Term Liabilities	$21.12M	$40.09M
Total Liabilities	$63.32M	$75.10M
YoY Change	-15.69%
SHAREHOLDERS EQUITY
Retained Earnings	-$192.0M	-$146.2M
YoY Change	31.35%
Common Stock	$2.000K	$1.000K
YoY Change	100.0%
Preferred Stock
YoY Change
Treasury Stock (at cost)	$0.00	$2.109M
YoY Change	-100.0%
Treasury Stock Shares
Shareholders Equity	$257.7M	-$131.9M	-$107.0M
YoY Change
Total Liabilities & Shareholders Equity	$321.0M	$162.8M
YoY Change	97.21%

Cashflow Statement

Concept	2019 Q4	2018 Q4	2017 Q4
OPERATING ACTIVITIES
Net Income	-$14.07M	-$7.310M	-$9.410M
YoY Change	92.48%	-22.32%
Depreciation, Depletion And Amortization	$4.860M	$3.680M
YoY Change	32.07%
Cash From Operating Activities	-$3.060M	-$790.0K
YoY Change	287.34%
INVESTING ACTIVITIES
Capital Expenditures	-$5.850M	-$7.330M
YoY Change	-20.19%
Acquisitions
YoY Change
Other Investing Activities	$38.32M	-$1.430M
YoY Change	-2779.72%
Cash From Investing Activities	$32.48M	-$8.760M
YoY Change	-470.78%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	1.930M	25.31M
YoY Change	-92.37%
NET CHANGE
Cash From Operating Activities	-3.060M	-790.0K
Cash From Investing Activities	32.48M	-8.760M
Cash From Financing Activities	1.930M	25.31M
Net Change In Cash	31.35M	15.76M
YoY Change	98.92%
FREE CASH FLOW
Cash From Operating Activities	-$3.060M	-$790.0K
Capital Expenditures	-$5.850M	-$7.330M
Free Cash Flow	$2.790M	$6.540M
YoY Change	-57.34%

Facts In Submission

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CY2019	dei	Entity File Number EntityFileNumber	001-38897
CY2019	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	DE
CY2019	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	27-5411834
CY2019	dei	Entity Address Address Line1 EntityAddressAddressLine1	475 Brannan Street, Suite 300
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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	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
CY2019	us-gaap	Net Income Loss NetIncomeLoss	-51550000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	-30935000	USD
CY2017	us-gaap	Net Income Loss NetIncomeLoss	-32450000	USD
CY2019	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	16553000	USD
CY2018	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	13400000	USD
CY2017	fsly	Amortization Of Deferred Rent AmortizationOfDeferredRent	265000	USD
CY2019	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	1909000	USD
CY2017	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	9642000	USD
CY2019	fsly	Amortization Of Deferred Rent AmortizationOfDeferredRent	-711000	USD
CY2019	us-gaap	Share Based Compensation ShareBasedCompensation	12145000	USD
CY2018	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	0	USD
CY2017	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	161000	USD
CY2018	fsly	Amortization Of Deferred Rent AmortizationOfDeferredRent	-340000	USD
CY2018	us-gaap	Share Based Compensation ShareBasedCompensation	4079000	USD
CY2017	us-gaap	Share Based Compensation ShareBasedCompensation	2809000	USD
CY2019	us-gaap	Provision For Doubtful Accounts ProvisionForDoubtfulAccounts	360000	USD
CY2018	us-gaap	Provision For Doubtful Accounts ProvisionForDoubtfulAccounts	599000	USD
CY2017	us-gaap	Provision For Doubtful Accounts ProvisionForDoubtfulAccounts	1024000	USD
CY2019	us-gaap	Fair Value Adjustment Of Warrants FairValueAdjustmentOfWarrants	2404000	USD
CY2018	us-gaap	Fair Value Adjustment Of Warrants FairValueAdjustmentOfWarrants	606000	USD
CY2017	us-gaap	Fair Value Adjustment Of Warrants FairValueAdjustmentOfWarrants	176000	USD
CY2019	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	591000	USD
CY2018	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	354000	USD
CY2017	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	18000	USD
CY2019	fsly	Interest Paidon Capital Lease InterestPaidonCapitalLease	364000	USD
CY2018	fsly	Interest Paidon Capital Lease InterestPaidonCapitalLease	203000	USD
CY2017	fsly	Interest Paidon Capital Lease InterestPaidonCapitalLease	105000	USD
CY2019	us-gaap	Gain Loss On Sale Of Property Plant Equipment GainLossOnSaleOfPropertyPlantEquipment	-108000	USD
CY2018	us-gaap	Gain Loss On Sale Of Property Plant Equipment GainLossOnSaleOfPropertyPlantEquipment	0	USD
CY2017	us-gaap	Gain Loss On Sale Of Property Plant Equipment GainLossOnSaleOfPropertyPlantEquipment	-113000	USD
CY2019	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	12767000	USD
CY2018	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	6234000	USD
CY2017	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	6043000	USD
CY2019	us-gaap	Increase Decrease In Prepaid Deferred Expense And Other Assets IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	2095000	USD
CY2018	us-gaap	Increase Decrease In Prepaid Deferred Expense And Other Assets IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	2325000	USD
CY2017	us-gaap	Increase Decrease In Prepaid Deferred Expense And Other Assets IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	3537000	USD
CY2019	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	2222000	USD
CY2018	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	-10000	USD
CY2017	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	94000	USD
CY2019	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	2391000	USD
CY2018	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	-372000	USD
CY2017	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	1109000	USD
CY2019	us-gaap	Increase Decrease In Accrued Liabilities IncreaseDecreaseInAccruedLiabilities	4401000	USD
CY2018	us-gaap	Increase Decrease In Accrued Liabilities IncreaseDecreaseInAccruedLiabilities	3902000	USD
CY2017	us-gaap	Increase Decrease In Accrued Liabilities IncreaseDecreaseInAccruedLiabilities	1009000	USD
CY2019	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-1274000	USD
CY2018	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	1182000	USD
CY2017	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	78000	USD
CY2019	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	-31303000	USD
CY2018	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	-16985000	USD
CY2017	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	-25861000	USD
CY2019	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	190980000	USD
CY2018	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	62660000	USD
CY2017	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	46071000	USD
CY2019	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	52589000	USD
CY2018	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	0	USD
CY2017	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	0	USD
CY2019	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	70813000	USD
CY2018	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	35210000	USD
CY2018	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	16702000	USD
CY2017	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	43539000	USD
CY2019	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	14609000	USD
CY2017	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	12099000	USD
CY2019	us-gaap	Payments For Software PaymentsForSoftware	4856000	USD
CY2018	us-gaap	Payments For Software PaymentsForSoftware	2955000	USD
CY2017	us-gaap	Payments For Software PaymentsForSoftware	1149000	USD
CY2019	us-gaap	Payments To Acquire Intangible Assets PaymentsToAcquireIntangibleAssets	635000	USD
CY2018	us-gaap	Payments To Acquire Intangible Assets PaymentsToAcquireIntangibleAssets	0	USD
CY2017	us-gaap	Payments To Acquire Intangible Assets PaymentsToAcquireIntangibleAssets	0	USD
CY2019	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-87678000	USD
CY2018	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-47107000	USD
CY2017	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-15780000	USD
CY2019	us-gaap	Proceeds From Issuance Initial Public Offering ProceedsFromIssuanceInitialPublicOffering	192510000	USD
CY2018	us-gaap	Proceeds From Issuance Initial Public Offering ProceedsFromIssuanceInitialPublicOffering	0	USD
CY2017	us-gaap	Proceeds From Issuance Initial Public Offering ProceedsFromIssuanceInitialPublicOffering	0	USD
CY2019	us-gaap	Proceeds From Notes Payable ProceedsFromNotesPayable	20300000	USD
CY2018	us-gaap	Proceeds From Notes Payable ProceedsFromNotesPayable	29411000	USD
CY2017	us-gaap	Proceeds From Notes Payable ProceedsFromNotesPayable	12774000	USD
CY2019	us-gaap	Payments Of Debt Issuance Costs PaymentsOfDebtIssuanceCosts	231000	USD
CY2018	us-gaap	Payments Of Debt Issuance Costs PaymentsOfDebtIssuanceCosts	257000	USD
CY2019	us-gaap	Repayments Of Notes Payable RepaymentsOfNotesPayable	49167000	USD
CY2018	us-gaap	Repayments Of Notes Payable RepaymentsOfNotesPayable	833000	USD
CY2017	us-gaap	Repayments Of Notes Payable RepaymentsOfNotesPayable	7383000	USD
CY2019	us-gaap	Repayments Of Long Term Capital Lease Obligations RepaymentsOfLongTermCapitalLeaseObligations	1370000	USD
CY2018	us-gaap	Repayments Of Long Term Capital Lease Obligations RepaymentsOfLongTermCapitalLeaseObligations	1215000	USD
CY2017	us-gaap	Repayments Of Long Term Capital Lease Obligations RepaymentsOfLongTermCapitalLeaseObligations	464000	USD
CY2019	us-gaap	Proceeds From Stock Plans ProceedsFromStockPlans	5402000	USD
CY2018	us-gaap	Proceeds From Stock Plans ProceedsFromStockPlans	0	USD
CY2017	us-gaap	Proceeds From Stock Plans ProceedsFromStockPlans	0	USD
CY2019	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	5579000	USD
CY2018	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	1561000	USD
CY2017	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	611000	USD
CY2019	fsly	Proceeds From Stock Options Exercised Early ProceedsFromStockOptionsExercisedEarly	520000	USD
CY2018	fsly	Proceeds From Stock Options Exercised Early ProceedsFromStockOptionsExercisedEarly	1054000	USD
CY2017	fsly	Proceeds From Stock Options Exercised Early ProceedsFromStockOptionsExercisedEarly	5000	USD
CY2019	fsly	Proceeds From Repayment Of Stockholders Note ProceedsFromRepaymentOfStockholdersNote	74000	USD
CY2018	fsly	Proceeds From Repayment Of Stockholders Note ProceedsFromRepaymentOfStockholdersNote	50000	USD
CY2017	fsly	Proceeds From Repayment Of Stockholders Note ProceedsFromRepaymentOfStockholdersNote	0	USD
CY2019	fsly	Payments For Repurchaseof Stock Options Exercised Early PaymentsForRepurchaseofStockOptionsExercisedEarly	0	USD
CY2018	fsly	Payments For Repurchaseof Stock Options Exercised Early PaymentsForRepurchaseofStockOptionsExercisedEarly	13000	USD
CY2017	fsly	Payments For Repurchaseof Stock Options Exercised Early PaymentsForRepurchaseofStockOptionsExercisedEarly	0	USD
CY2019	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	168148000	USD
CY2018	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	69637000	USD
CY2017	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	55406000	USD
CY2017	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	-32000	USD
CY2019	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	49266000	USD
CY2018	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	5567000	USD
CY2019	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	99000	USD
CY2018	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	22000	USD
CY2017	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	13733000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	36963000	USD
CY2017Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	31396000	USD
CY2016Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	17663000	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
CY2018	fsly	Warrants Issued WarrantsIssued	1639000	USD
CY2017Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	31396000	USD
CY2019	us-gaap	Interest Paid Net InterestPaidNet	5422000	USD
CY2019	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	361000	USD
CY2018	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	55000	USD
CY2017	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	166000	USD
CY2019	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	7071000	USD
CY2018	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	133000	USD
CY2018	us-gaap	Interest Paid Net InterestPaidNet	1833000	USD
CY2017	us-gaap	Interest Paid Net InterestPaidNet	996000	USD
CY2017	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	1838000	USD
CY2019	fsly	Vestingof Early Exercised Stock Options VestingofEarlyExercisedStockOptions	620000	USD
CY2018	fsly	Vestingof Early Exercised Stock Options VestingofEarlyExercisedStockOptions	337000	USD
CY2017	fsly	Vestingof Early Exercised Stock Options VestingofEarlyExercisedStockOptions	248000	USD
CY2019	us-gaap	Capital Lease Obligations Incurred CapitalLeaseObligationsIncurred	7380000	USD
CY2018	us-gaap	Capital Lease Obligations Incurred CapitalLeaseObligationsIncurred	429000	USD
CY2017	us-gaap	Capital Lease Obligations Incurred CapitalLeaseObligationsIncurred	4324000	USD
CY2019	fsly	Warrants Issued WarrantsIssued	0	USD
CY2017	fsly	Warrants Issued WarrantsIssued	0	USD
CY2019Q4	us-gaap	Cumulative Effect Of New Accounting Principle In Period Of Adoption CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	5727000	USD
CY2018Q4	us-gaap	Cumulative Effect Of New Accounting Principle In Period Of Adoption CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	0	USD
CY2017Q4	us-gaap	Cumulative Effect Of New Accounting Principle In Period Of Adoption CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	0	USD
CY2019	us-gaap	Conversion Of Stock Amount Converted1 ConversionOfStockAmountConverted1	5665000	USD
CY2018	us-gaap	Conversion Of Stock Amount Converted1 ConversionOfStockAmountConverted1	0	USD
CY2017	us-gaap	Conversion Of Stock Amount Converted1 ConversionOfStockAmountConverted1	0	USD
CY2019	fsly	Cashless Exercise Of Common Stock Warrants CashlessExerciseOfCommonStockWarrants	1036000	USD
CY2018	fsly	Cashless Exercise Of Common Stock Warrants CashlessExerciseOfCommonStockWarrants	0	USD
CY2017	fsly	Cashless Exercise Of Common Stock Warrants CashlessExerciseOfCommonStockWarrants	0	USD
CY2019	fsly	Initial Public Offering Costs Incurred But Not Yet Paid InitialPublicOfferingCostsIncurredButNotYetPaid	130000	USD
CY2018	fsly	Initial Public Offering Costs Incurred But Not Yet Paid InitialPublicOfferingCostsIncurredButNotYetPaid	0	USD
CY2017	fsly	Initial Public Offering Costs Incurred But Not Yet Paid InitialPublicOfferingCostsIncurredButNotYetPaid	0	USD
CY2019	us-gaap	Employee Service Share Based Compensation Allocation Of Recognized Period Costs Capitalized Amount EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount	441000	USD
CY2018	us-gaap	Employee Service Share Based Compensation Allocation Of Recognized Period Costs Capitalized Amount EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount	0	USD
CY2017	us-gaap	Employee Service Share Based Compensation Allocation Of Recognized Period Costs Capitalized Amount EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount	0	USD
CY2019Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	16142000	USD
CY2018Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	36963000	USD
CY2017Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	31309000	USD
CY2019Q4	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	70087000	USD
CY2018Q4	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	0	USD
CY2017Q4	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	87000	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
CY2017Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	31396000	USD
CY2019	us-gaap	Nature Of Operations NatureOfOperations	Nature of Business<div style="line-height:120%;padding-bottom:16px;text-align:left;text-indent:36px;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">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. Our edge network spans </span><span style="font-family:inherit;font-size:10pt;"><span>68</span></span><span style="font-family:inherit;font-size:10pt;"> Points-of-Presence ("POPs") across </span><span style="font-family:inherit;font-size:10pt;"><span>53</span></span><span style="font-family:inherit;font-size:10pt;"> markets, as of </span><span style="font-family:inherit;font-size:10pt;">December 31, 2019</span><span style="font-family:inherit;font-size:10pt;">. We were incorporated in Delaware in 2011 and are headquartered in San Francisco, California.</span></div><div style="line-height:120%;padding-bottom:16px;text-align:left;text-indent:36px;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">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="line-height:120%;padding-bottom:16px;text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;font-style:italic;font-weight:bold;">Stock Split</span></div><div style="line-height:120%;padding-bottom:16px;text-align:left;text-indent:36px;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">On May 3, 2019, we implemented a 1-for-</span><span style="font-family:inherit;font-size:10pt;">2</span><span style="font-family:inherit;font-size:10pt;"> reverse stock split of our stock. All shares of common stock, stock-based instruments, and per-share data included in these financial statements give effect to the stock split and the changes in authorized shares have been adjusted retroactively for all periods presented.</span></div><div style="line-height:120%;padding-bottom:16px;text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;font-style:italic;font-weight:bold;">Initial Public Offering ("IPO")</span></div><span style="font-family:inherit;font-size:10pt;">On May 21, 2019 we completed an IPO in which we sold </span><span style="font-family:inherit;font-size:10pt;"><span>12,937,500</span></span><span style="font-family:inherit;font-size:10pt;"> shares of our newly authorized Class A common stock, which included </span><span style="font-family:inherit;font-size:10pt;"><span>1,687,500</span></span><span style="font-family:inherit;font-size:10pt;"> shares sold pursuant to the exercise by the underwriters of an option to purchase additional shares, at the public offering price of </span><span style="font-family:inherit;font-size:10pt;"><span>$16.00</span></span><span style="font-family:inherit;font-size:10pt;"> per share. We received net proceeds of </span><span style="font-family:inherit;font-size:10pt;"><span>$192.5 million</span></span><span style="font-family:inherit;font-size:10pt;">, after deducting underwriting discounts and commissions, from sales of our shares in the IPO. The net proceeds include additional proceeds of </span><span style="font-family:inherit;font-size:10pt;"><span>$25.1 million</span></span><span style="font-family:inherit;font-size:10pt;">, net of underwriters' discounts and commissions, from the exercise of the underwriters' option to purchase an additional </span><span style="font-family:inherit;font-size:10pt;"><span>1,687,500</span></span><span style="font-family:inherit;font-size:10pt;"> 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. Immediately upon the closing of the IPO, all shares of convertible preferred stock then outstanding were converted into </span><span style="font-family:inherit;font-size:10pt;"><span>53,630,213</span></span><span style="font-family:inherit;font-size:10pt;"> shares of Class B common stock on a </span><span style="font-family:inherit;font-size:10pt;"><span>one</span></span>-to-one basis.
CY2019Q4	fsly	Pointsof Presence PointsofPresence	68	location
CY2019Q4	fsly	Operating Markets OperatingMarkets	53	market
CY2019	us-gaap	Basis Of Accounting BasisOfAccounting	<div style="line-height:120%;padding-bottom:16px;text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;font-style:italic;font-weight:bold;">Basis of Presentation</span></div><div style="line-height:120%;padding-bottom:16px;text-align:left;text-indent:36px;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">The consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles ("U.S. GAAP"). </span></div><div style="line-height:120%;padding-bottom:16px;text-align:left;text-indent:36px;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">Certain changes in presentation have been made to conform the prior period presentation to the current period reporting. We have reclassified a portion of sales from marketable securities to maturities of marketable securities line item in the Consolidated Statements of Cash Flows. We have also reclassified a portion of purchases of property and equipment to the capitalized internal-use software line item of the Consolidated Statements of Cash Flows. We have also reclassified a portion of the proceeds from borrowings under notes payable to the payments of debt issuance costs line item of the Consolidated Statement of Cash Flows. In addition, as a result of the adoption of ASU 2016-18 (Topic 230), we have shown the changes in the total of cash, cash equivalents, and restricted cash in the Consolidated Statements of Cash Flows. We have also reclassified a portion of other accrued liabilities to the accrued colocation and bandwidth costs line in the Accrued Expenses section of Footnote 5, "Balance Sheet Information".</span></div>
CY2019	us-gaap	Use Of Estimates UseOfEstimates	<div style="line-height:120%;padding-bottom:16px;text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;font-style:italic;font-weight:bold;">Use of Estimates</span></div><div style="line-height:120%;padding-bottom:16px;text-align:left;text-indent:36px;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">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, useful lives and realizability of long-lived assets, income tax reserves, and accounting for stock-based </span></div><div style="line-height:120%;padding-bottom:16px;text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">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>
CY2019Q4	us-gaap	Restricted Cash And Cash Equivalents At Carrying Value RestrictedCashAndCashEquivalentsAtCarryingValue	70100000	USD
CY2018Q4	us-gaap	Restricted Cash And Cash Equivalents At Carrying Value RestrictedCashAndCashEquivalentsAtCarryingValue	0	USD
CY2019	us-gaap	Concentration Risk Credit Risk ConcentrationRiskCreditRisk	<div style="line-height:120%;padding-bottom:16px;text-align:left;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;font-style:italic;font-weight:bold;">Concentrations of Credit Risk</span></div><div style="line-height:120%;padding-bottom:16px;text-align:left;text-indent:36px;font-size:10pt;"><span style="font-family:inherit;font-size:10pt;">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 to which we make substantial sales. Our customer base consists of a large number of geographically dispersed customers diversified across several industries. To reduce 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.
CY2018Q4	us-gaap	Deferred Offering Costs DeferredOfferingCosts	300000	USD
CY2019	us-gaap	Advertising Expense AdvertisingExpense	1400000	USD
CY2018	us-gaap	Advertising Expense AdvertisingExpense	500000	USD
CY2017	us-gaap	Advertising Expense AdvertisingExpense	700000	USD
CY2019	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	-51318000	USD
CY2019Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	10112000	USD
CY2019Q4	us-gaap	Assets Assets	320969000	USD
CY2019Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	-192009000	USD
CY2019Q4	us-gaap	Stockholders Equity StockholdersEquity	257652000	USD
CY2019Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	320969000	USD
CY2019	us-gaap	Selling And Marketing Expense SellingAndMarketingExpense	71097000	USD
CY2019	us-gaap	Operating Expenses OperatingExpenses	158688000	USD
CY2019	us-gaap	Operating Income Loss OperatingIncomeLoss	-46548000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	-51058000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	-51550000	USD
CY2019	us-gaap	Revenue From Contract With Customer Including Assessed Tax RevenueFromContractWithCustomerIncludingAssessedTax	200462000	USD
CY2018	us-gaap	Revenue From Contract With Customer Including Assessed Tax RevenueFromContractWithCustomerIncludingAssessedTax	144563000	USD
CY2017	us-gaap	Revenue From Contract With Customer Including Assessed Tax RevenueFromContractWithCustomerIncludingAssessedTax	104900000	USD
CY2019Q4	fsly	Enterprise Customer Threshold EnterpriseCustomerThreshold	100000	USD
CY2019	us-gaap	Revenue From Contract With Customer Including Assessed Tax RevenueFromContractWithCustomerIncludingAssessedTax	200462000	USD
CY2018	us-gaap	Revenue From Contract With Customer Including Assessed Tax RevenueFromContractWithCustomerIncludingAssessedTax	144563000	USD
CY2017	us-gaap	Revenue From Contract With Customer Including Assessed Tax RevenueFromContractWithCustomerIncludingAssessedTax	104900000	USD
CY2019Q4	us-gaap	Contract With Customer Asset Net ContractWithCustomerAssetNet	271000	USD
CY2018Q4	us-gaap	Contract With Customer Asset Net ContractWithCustomerAssetNet	0	USD
CY2019Q4	us-gaap	Contract With Customer Liability ContractWithCustomerLiability	317000	USD
CY2019Q1	us-gaap	Contract With Customer Liability ContractWithCustomerLiability	1622000	USD
CY2019	us-gaap	Contract With Customer Liability Revenue Recognized ContractWithCustomerLiabilityRevenueRecognized	1539000	USD
CY2019Q4	us-gaap	Revenue Remaining Performance Obligation RevenueRemainingPerformanceObligation	70700000	USD
CY2019Q4	us-gaap	Revenue Remaining Performance Obligation Percentage RevenueRemainingPerformanceObligationPercentage	0.89
CY2019Q4	us-gaap	Revenue Remaining Performance Obligation Expected Timing Of Satisfaction Period1 RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1	P12M
CY2019Q4	us-gaap	Capitalized Contract Cost Amortization Period CapitalizedContractCostAmortizationPeriod	P5Y
CY2019Q4	us-gaap	Capitalized Contract Cost Net Noncurrent CapitalizedContractCostNetNoncurrent	6804000	USD
CY2019Q1	us-gaap	Capitalized Contract Cost Net Noncurrent CapitalizedContractCostNetNoncurrent	5727000	USD
CY2019	us-gaap	Capitalized Contract Cost Amortization CapitalizedContractCostAmortization	2300000	USD
CY2019Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	16142000	USD
CY2018Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	36963000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Securities Current AvailableForSaleSecuritiesDebtSecuritiesCurrent	114967000	USD
CY2018Q4	us-gaap	Available For Sale Securities Debt Securities Current AvailableForSaleSecuritiesDebtSecuritiesCurrent	46679000	USD
CY2019Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	114870000	USD
CY2019Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	98000	USD
CY2019Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	1000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	114967000	USD
CY2018Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	46703000	USD
CY2018Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	0	USD
CY2018Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	24000	USD
CY2018Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	46679000	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Number Of Positions DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions	0	security
CY2019Q4	us-gaap	Cash Equivalents At Carrying Value CashEquivalentsAtCarryingValue	4519000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Securities Current AvailableForSaleSecuritiesDebtSecuritiesCurrent	114967000	USD
CY2019Q4	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	70087000	USD
CY2019Q4	us-gaap	Assets Fair Value Disclosure AssetsFairValueDisclosure	189573000	USD
CY2018Q4	us-gaap	Cash Equivalents At Carrying Value CashEquivalentsAtCarryingValue	4417000	USD
CY2018Q4	us-gaap	Available For Sale Securities Debt Securities Current AvailableForSaleSecuritiesDebtSecuritiesCurrent	46679000	USD
CY2018Q4	us-gaap	Assets Fair Value Disclosure AssetsFairValueDisclosure	51096000	USD
CY2018Q4	fsly	Convertible Preferred Stock Warrant Liability ConvertiblePreferredStockWarrantLiability	3261000	USD
CY2018Q4	us-gaap	Liabilities Fair Value Disclosure LiabilitiesFairValueDisclosure	3261000	USD
CY2018Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliations Recurring Basis Liability Value FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue	3261000	USD
CY2019	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Liability Gain Loss Included In Earnings FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings	-2404000	USD
CY2019	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Liability Transfers Out Of Level3 FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersOutOfLevel3	5665000	USD
CY2019Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliations Recurring Basis Liability Value FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue	0	USD
CY2018Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	1679000	USD
CY2017Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	1119000	USD
CY2019	us-gaap	Provision For Doubtful Accounts ProvisionForDoubtfulAccounts	360000	USD
CY2018	us-gaap	Provision For Doubtful Accounts ProvisionForDoubtfulAccounts	599000	USD
CY2019	us-gaap	Allowance For Doubtful Accounts Receivable Write Offs AllowanceForDoubtfulAccountsReceivableWriteOffs	223000	USD
CY2018	us-gaap	Allowance For Doubtful Accounts Receivable Write Offs AllowanceForDoubtfulAccountsReceivableWriteOffs	39000	USD
CY2019Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	1816000	USD
CY2018Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	1679000	USD
CY2019Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	108276000	USD
CY2018Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	77975000	USD
CY2019Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	48239000	USD
CY2018Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	35621000	USD
CY2019Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	60037000	USD
CY2018Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	42354000	USD
CY2019	us-gaap	Depreciation Depreciation	16400000	USD
CY2018	us-gaap	Depreciation Depreciation	13300000	USD
CY2019Q4	us-gaap	Employee Related Liabilities Current EmployeeRelatedLiabilitiesCurrent	8734000	USD
CY2018Q4	us-gaap	Employee Related Liabilities Current EmployeeRelatedLiabilitiesCurrent	3952000	USD
CY2019Q4	us-gaap	Sales And Excise Tax Payable Current SalesAndExciseTaxPayableCurrent	3938000	USD
CY2018Q4	us-gaap	Sales And Excise Tax Payable Current SalesAndExciseTaxPayableCurrent	3077000	USD
CY2019Q4	fsly	Accrued Colocation And Bandwidth Costs AccruedColocationAndBandwidthCosts	3237000	USD
CY2018Q4	fsly	Accrued Colocation And Bandwidth Costs AccruedColocationAndBandwidthCosts	3049000	USD
CY2019Q4	us-gaap	Other Accrued Liabilities Current OtherAccruedLiabilitiesCurrent	3969000	USD
CY2018Q4	us-gaap	Other Accrued Liabilities Current OtherAccruedLiabilitiesCurrent	5457000	USD
CY2019Q4	us-gaap	Accrued Liabilities Current AccruedLiabilitiesCurrent	19878000	USD
CY2018Q4	us-gaap	Accrued Liabilities Current AccruedLiabilitiesCurrent	15535000	USD
CY2019Q4	fsly	Liability For Early Exercised Stock Options Current LiabilityForEarlyExercisedStockOptionsCurrent	467000	USD
CY2018Q4	fsly	Liability For Early Exercised Stock Options Current LiabilityForEarlyExercisedStockOptionsCurrent	597000	USD
CY2019Q4	us-gaap	Contract With Customer Liability Current ContractWithCustomerLiabilityCurrent	317000	USD
CY2018Q4	us-gaap	Contract With Customer Liability Current ContractWithCustomerLiabilityCurrent	1622000	USD
CY2019Q4	fsly	Accrued Computer And Networking Equipment AccruedComputerAndNetworkingEquipment	7060000	USD
CY2018Q4	fsly	Accrued Computer And Networking Equipment AccruedComputerAndNetworkingEquipment	0	USD
CY2019Q4	us-gaap	Other Sundry Liabilities Current OtherSundryLiabilitiesCurrent	325000	USD
CY2018Q4	us-gaap	Other Sundry Liabilities Current OtherSundryLiabilitiesCurrent	293000	USD
CY2019Q4	us-gaap	Other Liabilities Current OtherLiabilitiesCurrent	8169000	USD
CY2018Q4	us-gaap	Other Liabilities Current OtherLiabilitiesCurrent	2512000	USD
CY2019Q4	us-gaap	Deferred Rent Credit Noncurrent DeferredRentCreditNoncurrent	634000	USD
CY2018Q4	us-gaap	Deferred Rent Credit Noncurrent DeferredRentCreditNoncurrent	272000	USD
CY2019Q4	us-gaap	Other Sundry Liabilities Noncurrent OtherSundryLiabilitiesNoncurrent	404000	USD
CY2018Q4	us-gaap	Other Sundry Liabilities Noncurrent OtherSundryLiabilitiesNoncurrent	375000	USD
CY2019Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	1038000	USD
CY2018Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	647000	USD
CY2017	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	25000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-12000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	232000	USD
CY2018Q4	us-gaap	Goodwill Goodwill	360000	USD
CY2017Q4	us-gaap	Goodwill Goodwill	382000	USD
CY2019	us-gaap	Goodwill Foreign Currency Translation Gain Loss GoodwillForeignCurrencyTranslationGainLoss	12000	USD
CY2018	us-gaap	Goodwill Foreign Currency Translation Gain Loss GoodwillForeignCurrencyTranslationGainLoss	-22000	USD
CY2019Q4	us-gaap	Goodwill Goodwill	372000	USD
CY2018Q4	us-gaap	Goodwill Goodwill	360000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Gross FiniteLivedIntangibleAssetsGross	1487000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	362000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	1125000	USD
CY2018Q4	us-gaap	Finite Lived Intangible Assets Gross FiniteLivedIntangibleAssetsGross	852000	USD
CY2018Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	242000	USD
CY2018Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	610000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Next Twelve Months FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths	155000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Two FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo	158000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Three FiniteLivedIntangibleAssetsAmortizationExpenseYearThree	158000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Four FiniteLivedIntangibleAssetsAmortizationExpenseYearFour	148000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Five FiniteLivedIntangibleAssetsAmortizationExpenseYearFive	145000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense After Year Five FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive	361000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	1125000	USD
CY2019	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	100000	USD
CY2019Q4	us-gaap	Capital Lease Obligations CapitalLeaseObligations	9500000	USD
CY2018Q4	us-gaap	Capital Lease Obligations CapitalLeaseObligations	3500000	USD
CY2019Q4	us-gaap	Capital Lease Obligations CapitalLeaseObligations	9549000	USD
CY2018Q4	us-gaap	Capital Lease Obligations CapitalLeaseObligations	3538000	USD
CY2019Q4	us-gaap	Capital Lease Obligations Current CapitalLeaseObligationsCurrent	4472000	USD
CY2018Q4	us-gaap	Capital Lease Obligations Current CapitalLeaseObligationsCurrent	1370000	USD
CY2019Q4	us-gaap	Capital Lease Obligations Noncurrent CapitalLeaseObligationsNoncurrent	5077000	USD
CY2018Q4	us-gaap	Capital Lease Obligations Noncurrent CapitalLeaseObligationsNoncurrent	2168000	USD
CY2019Q4	us-gaap	Long Term Debt And Capital Lease Obligations LongTermDebtAndCapitalLeaseObligations	25158000	USD
CY2018Q4	us-gaap	Long Term Debt And Capital Lease Obligations LongTermDebtAndCapitalLeaseObligations	39439000	USD
CY2019Q4	us-gaap	Long Term Debt And Capital Lease Obligations Repayments Of Principal In Next Twelve Months LongTermDebtAndCapitalLeaseObligationsRepaymentsOfPrincipalInNextTwelveMonths	4472000	USD
CY2019Q4	fsly	Long Term Debt And Capital Lease Obligations Maturities Interest Due Next Twelve Months LongTermDebtAndCapitalLeaseObligationsMaturitiesInterestDueNextTwelveMonths	1210000	USD
CY2019Q4	fsly	Longterm Debtand Capital Lease Obligations Maturities Total Payments Due Next Twelve Months LongtermDebtandCapitalLeaseObligationsMaturitiesTotalPaymentsDueNextTwelveMonths	5682000	USD
CY2019Q4	us-gaap	Long Term Debt And Capital Lease Obligations Maturities Repayments Of Principal In Year Two LongTermDebtAndCapitalLeaseObligationsMaturitiesRepaymentsOfPrincipalInYearTwo	3759000	USD
CY2019Q4	fsly	Long Term Debt And Capital Lease Obligations Maturities Interest Due Year Two LongTermDebtAndCapitalLeaseObligationsMaturitiesInterestDueYearTwo	992000	USD
CY2019Q4	fsly	Longterm Debtand Capital Lease Obligations Maturities Total Payments Due Year Two LongtermDebtandCapitalLeaseObligationsMaturitiesTotalPaymentsDueYearTwo	4751000	USD
CY2019Q4	us-gaap	Long Term Debt And Capital Lease Obligations Maturities Repayments Of Principal In Year Three LongTermDebtAndCapitalLeaseObligationsMaturitiesRepaymentsOfPrincipalInYearThree	21618000	USD
CY2019Q4	fsly	Long Term Debt And Capital Lease Obligations Maturities Interest Due Year Three LongTermDebtAndCapitalLeaseObligationsMaturitiesInterestDueYearThree	794000	USD
CY2019Q4	fsly	Longterm Debtand Capital Lease Obligations Maturities Total Payments Due Year Three LongtermDebtandCapitalLeaseObligationsMaturitiesTotalPaymentsDueYearThree	22412000	USD
CY2019Q4	us-gaap	Long Term Debt And Capital Lease Obligations Maturities Repayments Of Principal In Year Four LongTermDebtAndCapitalLeaseObligationsMaturitiesRepaymentsOfPrincipalInYearFour	0	USD
CY2019Q4	fsly	Long Term Debt And Capital Lease Obligations Maturities Interest Due Year Four LongTermDebtAndCapitalLeaseObligationsMaturitiesInterestDueYearFour	0	USD
CY2019Q4	fsly	Longterm Debtand Capital Lease Obligations Maturities Total Payments Due Year Four LongtermDebtandCapitalLeaseObligationsMaturitiesTotalPaymentsDueYearFour	0	USD
CY2019Q4	fsly	Longterm Debtand Capital Lease Obligations Maturities Repaymentsof Principal LongtermDebtandCapitalLeaseObligationsMaturitiesRepaymentsofPrincipal	29849000	USD
CY2019Q4	fsly	Long Term Debt And Capital Lease Obligations Interest Due LongTermDebtAndCapitalLeaseObligationsInterestDue	2996000	USD
CY2019Q4	fsly	Longterm Debtand Capital Lease Obligations Maturities Total Payments Due LongtermDebtandCapitalLeaseObligationsMaturitiesTotalPaymentsDue	32845000	USD
CY2019	us-gaap	Interest Expense Debt InterestExpenseDebt	5200000	USD
CY2018	us-gaap	Interest Expense Debt InterestExpenseDebt	1900000	USD
CY2017	us-gaap	Interest Expense Debt InterestExpenseDebt	1100000	USD
CY2019Q2	fsly	Convertible Preferred Stock Warrant Liability ConvertiblePreferredStockWarrantLiability	5665000	USD
CY2018Q4	fsly	Convertible Preferred Stock Warrant Liability ConvertiblePreferredStockWarrantLiability	3261000	USD
CY2019Q4	us-gaap	Operating Leases Future Minimum Payments Due Current OperatingLeasesFutureMinimumPaymentsDueCurrent	4856000	USD
CY2019Q4	us-gaap	Operating Leases Future Minimum Payments Receivable Current OperatingLeasesFutureMinimumPaymentsReceivableCurrent	1219000	USD
CY2019Q4	fsly	Operating Leases Payments Net Of Sublease Income Due Next Twelve Months OperatingLeasesPaymentsNetOfSubleaseIncomeDueNextTwelveMonths	3637000	USD
CY2019Q4	us-gaap	Operating Leases Future Minimum Payments Due In Two Years OperatingLeasesFutureMinimumPaymentsDueInTwoYears	6143000	USD
CY2019Q4	us-gaap	Operating Leases Future Minimum Payments Receivable In Two Years OperatingLeasesFutureMinimumPaymentsReceivableInTwoYears	0	USD
CY2019Q4	fsly	Operating Leases Payments Net Of Sublease Income Due Year Two OperatingLeasesPaymentsNetOfSubleaseIncomeDueYearTwo	6143000	USD
CY2019Q4	us-gaap	Operating Leases Future Minimum Payments Due In Three Years OperatingLeasesFutureMinimumPaymentsDueInThreeYears	5463000	USD
CY2019Q4	us-gaap	Operating Leases Future Minimum Payments Receivable In Three Years OperatingLeasesFutureMinimumPaymentsReceivableInThreeYears	0	USD
CY2019Q4	fsly	Operating Leases Payments Net Of Sublease Income Due Year Three OperatingLeasesPaymentsNetOfSubleaseIncomeDueYearThree	5463000	USD
CY2019Q4	us-gaap	Operating Leases Future Minimum Payments Due In Four Years OperatingLeasesFutureMinimumPaymentsDueInFourYears	5627000	USD
CY2019Q4	us-gaap	Operating Leases Future Minimum Payments Receivable In Four Years OperatingLeasesFutureMinimumPaymentsReceivableInFourYears	0	USD
CY2019Q4	fsly	Operating Leases Payments Net Of Sublease Income Due Year Four OperatingLeasesPaymentsNetOfSubleaseIncomeDueYearFour	5627000	USD
CY2019Q4	us-gaap	Operating Leases Future Minimum Payments Due In Five Years OperatingLeasesFutureMinimumPaymentsDueInFiveYears	5796000	USD
CY2019Q4	us-gaap	Operating Leases Future Minimum Payments Receivable In Five Years OperatingLeasesFutureMinimumPaymentsReceivableInFiveYears	0	USD
CY2019Q4	fsly	Operating Leases Payments Net Of Sublease Income Due Year Five OperatingLeasesPaymentsNetOfSubleaseIncomeDueYearFive	5796000	USD
CY2019Q4	us-gaap	Operating Leases Future Minimum Payments Due Thereafter OperatingLeasesFutureMinimumPaymentsDueThereafter	15794000	USD
CY2019Q4	us-gaap	Operating Leases Future Minimum Payments Receivable Thereafter OperatingLeasesFutureMinimumPaymentsReceivableThereafter	0	USD
CY2019Q4	fsly	Operating Leases Payments Net Of Sublease Income Due Thereafter OperatingLeasesPaymentsNetOfSubleaseIncomeDueThereafter	15794000	USD
CY2019Q4	us-gaap	Operating Leases Future Minimum Payments Due OperatingLeasesFutureMinimumPaymentsDue	43679000	USD
CY2019Q4	us-gaap	Operating Leases Future Minimum Payments Receivable OperatingLeasesFutureMinimumPaymentsReceivable	1219000	USD
CY2019Q4	fsly	Operating Leases Payments Net Of Sublease Income Due OperatingLeasesPaymentsNetOfSubleaseIncomeDue	42460000	USD
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod	691000	shares
CY2019	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	7200000	USD
CY2018	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	6900000	USD
CY2019	us-gaap	Operating Leases Income Statement Sublease Revenue OperatingLeasesIncomeStatementSubleaseRevenue	1200000	USD
CY2018	us-gaap	Operating Leases Income Statement Sublease Revenue OperatingLeasesIncomeStatementSubleaseRevenue	900000	USD
CY2019Q4	us-gaap	Purchase Obligation Due In Next Twelve Months PurchaseObligationDueInNextTwelveMonths	46929000	USD
CY2019Q4	us-gaap	Purchase Obligation Due In Second Year PurchaseObligationDueInSecondYear	12880000	USD
CY2019Q4	us-gaap	Purchase Obligation Due In Third Year PurchaseObligationDueInThirdYear	4457000	USD
CY2019Q4	us-gaap	Purchase Obligation Due In Fourth Year PurchaseObligationDueInFourthYear	142000	USD
CY2019Q4	us-gaap	Purchase Obligation Due In Fifth Year PurchaseObligationDueInFifthYear	63000	USD
CY2019Q4	us-gaap	Purchase Obligation PurchaseObligation	64471000	USD
CY2018Q4	fsly	Convertible Preferred Stock Number Of Series ConvertiblePreferredStockNumberOfSeries	7	series_of_stock
CY2018Q4	us-gaap	Temporary Equity Par Or Stated Value Per Share TemporaryEquityParOrStatedValuePerShare	0.00002
CY2019Q4	us-gaap	Temporary Equity Shares Outstanding TemporaryEquitySharesOutstanding	0	shares
CY2018Q4	us-gaap	Temporary Equity Shares Authorized TemporaryEquitySharesAuthorized	54148643	shares
CY2018Q4	us-gaap	Temporary Equity Shares Issued TemporaryEquitySharesIssued	53630213	shares
CY2018Q4	us-gaap	Temporary Equity Carrying Amount Attributable To Parent TemporaryEquityCarryingAmountAttributableToParent	219584000	USD
CY2018Q4	us-gaap	Temporary Equity Liquidation Preference TemporaryEquityLiquidationPreference	220037000	USD
CY2019Q2	us-gaap	Temporary Equity Shares Authorized TemporaryEquitySharesAuthorized	10000000	shares
CY2019Q2	us-gaap	Temporary Equity Par Or Stated Value Per Share TemporaryEquityParOrStatedValuePerShare	0.00002
CY2019Q4	us-gaap	Temporary Equity Shares Issued TemporaryEquitySharesIssued	0	shares
CY2016Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	8467000	shares
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CY2016Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	P8Y6M
CY2018	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested In Period Fair Value1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1	3600000	USD
CY2016Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue	7480000	USD
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	3008000	shares
CY2017	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice	2.90
CY2017	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	414000	shares
CY2016Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	1.54
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice	1.88
CY2017Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	10370000	shares
CY2017Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	1.92
CY2017Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	P8Y
CY2017Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue	16901000	USD
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	3984000	shares
CY2018	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice	5.32
CY2018	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	1264000	shares
CY2018	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	2.10
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod	880000	shares
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice	2.64
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
CY2018Q4	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
CY2019Q4	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
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Exercisable Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber	6994000	shares
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Exercisable Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice	2.68
CY2019Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested And Expected To Vest Exercisable Weighted Average Remaining Contractual Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageRemainingContractualTerm1	P6Y6M
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Exercisable Aggregate Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue	121610000	USD
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	32600000	USD
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	3000000.0	USD
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	700000	USD
CY2019	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested In Period Fair Value1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1	6100000	USD
CY2019Q4	us-gaap	Undistributed Earnings Of Foreign Subsidiaries UndistributedEarningsOfForeignSubsidiaries	0	USD
CY2017	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested In Period Fair Value1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1	2900000	USD
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
CY2018Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	28342000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	0	USD
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	1.78
CY2017	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	1.56
CY2019Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Number Of Shares SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares	199895	shares
CY2018Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Number Of Shares SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares	244658	shares
CY2017Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Number Of Shares SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares	137831	shares
CY2018Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Number Of Shares SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares	245000	shares
CY2017Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Number Of Shares SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares	138000	shares
CY2016Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Number Of Shares SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares	597000	shares
CY2019	fsly	Share Based Compensation Arrangement By Share Based Payment Award Options Nonvested Exercised Number Of Shares ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsNonvestedExercisedNumberOfShares	117000	shares
CY2018	fsly	Share Based Compensation Arrangement By Share Based Payment Award Options Nonvested Exercised Number Of Shares ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsNonvestedExercisedNumberOfShares	238000	shares
CY2017	fsly	Share Based Compensation Arrangement By Share Based Payment Award Options Nonvested Exercised Number Of Shares ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsNonvestedExercisedNumberOfShares	2000	shares
CY2019	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested Number Of Shares SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares	162000	shares
CY2018	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested Number Of Shares SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares	120000	shares
CY2017	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested Number Of Shares SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares	461000	shares
CY2019	fsly	Share Based Compensation Arrangement By Share Based Payment Award Options Nonvested Repurchased In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsNonvestedRepurchasedInPeriod	0	shares
CY2018	fsly	Share Based Compensation Arrangement By Share Based Payment Award Options Nonvested Repurchased In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsNonvestedRepurchasedInPeriod	11000	shares
CY2017	fsly	Share Based Compensation Arrangement By Share Based Payment Award Options Nonvested Repurchased In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsNonvestedRepurchasedInPeriod	0	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
CY2017Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Number Of Shares SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares	138000	shares
CY2019Q4	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Stock Options EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions	18200000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	492000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	185000	USD
CY2017	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	208000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	285000	USD
CY2018Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	212000	USD
CY2019Q4	fsly	Deferred Tax Liabilities State Taxes DeferredTaxLiabilitiesStateTaxes	2034000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	30750000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	25558000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	1753000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	1780000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Goodwill And Intangible Assets DeferredTaxAssetsGoodwillAndIntangibleAssets	642000	USD
CY2018Q4	fsly	Deferred Tax Liabilities State Taxes DeferredTaxLiabilitiesStateTaxes	1706000	USD
CY2019Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	2319000	USD
CY2018Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	1918000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	33781000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	0	USD
CY2019	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	12145000	USD
CY2018	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	4079000	USD
CY2017	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	2809000	USD
CY2019	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	13540000	shares
CY2018	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	62240000	shares
CY2018Q4	us-gaap	Deferred Tax Assets Goodwill And Intangible Assets DeferredTaxAssetsGoodwillAndIntangibleAssets	344000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	36100000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	30260000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	-30970000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	-20644000	USD
CY2017	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	-23372000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Foreign IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign	-20088000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Before Income Taxes Foreign IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign	-10291000	USD
CY2017	us-gaap	Income Loss From Continuing Operations Before Income Taxes Foreign IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign	-8870000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	-51058000	USD
CY2017	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	-32242000	USD
CY2019	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	0	USD
CY2018	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	0	USD
CY2017	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	0	USD
CY2019	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	106000	USD
CY2018	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	81000	USD
CY2017	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	68000	USD
CY2019	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	386000	USD
CY2018	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	104000	USD
CY2017	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	140000	USD
CY2019	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	0	USD
CY2018	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	0	USD
CY2017	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	0	USD
CY2019	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	0	USD
CY2018	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	0	USD
CY2017	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	0	USD
CY2019	us-gaap	Deferred Foreign Income Tax Expense Benefit DeferredForeignIncomeTaxExpenseBenefit	0	USD
CY2018	us-gaap	Deferred Foreign Income Tax Expense Benefit DeferredForeignIncomeTaxExpenseBenefit	0	USD
CY2017	us-gaap	Deferred Foreign Income Tax Expense Benefit DeferredForeignIncomeTaxExpenseBenefit	0	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.21
CY2018	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.21
CY2017	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.34
CY2019	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0
CY2018	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0
CY2017	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	-0.03
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Change In Deferred Tax Assets Valuation Allowance EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance	-0.12
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Change In Deferred Tax Assets Valuation Allowance EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance	-0.11
CY2017	us-gaap	Effective Income Tax Rate Reconciliation Change In Deferred Tax Assets Valuation Allowance EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance	0.13
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Foreign Income Tax Rate Differential EffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferential	-0.08
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Foreign Income Tax Rate Differential EffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferential	-0.07
CY2017	us-gaap	Effective Income Tax Rate Reconciliation Foreign Income Tax Rate Differential EffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferential	-0.10
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	0
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	0
CY2017	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	-0.32
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	-0.02
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	-0.04
CY2017	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	-0.03
CY2019	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	-0.01
CY2018	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	-0.01
CY2017	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	-0.01
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals DeferredTaxAssetsTaxDeferredExpenseReservesAndAccruals	1839000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals DeferredTaxAssetsTaxDeferredExpenseReservesAndAccruals	1892000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Share Based Compensation Cost DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost	1116000	USD
CY2018Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Share Based Compensation Cost DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost	686000	USD
CY2019Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	0	USD
CY2019	us-gaap	Number Of Reportable Segments NumberOfReportableSegments	1	segment
CY2019Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	60037000	USD
CY2018Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	42354000	USD

Files In Submission

Name	View Source	Status
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$FSLY
Fastly Inc Stock $fsly

2019 Q4 Form 10-K Financial Statement

#000151741320000043 Filed on March 04, 2020

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$FSLY Fastly Inc Stock $fsly

2019 Q4 Form 10-K Financial Statement

#000151741320000043 Filed on March 04, 2020

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$FSLY
Fastly Inc Stock $fsly