$CSTL
CASTLE BIOSCIENCES INC Stock $cstl

$cstl Overview Financials Valuation SEC Filings Company Website

2020 Q4 Form 10-K Financial Statement

#000144736221000047 Filed on March 11, 2021

Income Statement

Concept	2020 Q4	2020 Q3	2020 Q2
Revenue	$17.30M	$15.22M	$12.72M
YoY Change	-1.91%	3.0%	18.4%
Cost Of Revenue	$2.670M	$2.475M	$2.146M
YoY Change	32.84%	44.91%	7.68%
Gross Profit	$14.63M	$12.74M	$10.57M
YoY Change	-6.39%	-2.48%	20.84%
Gross Profit Margin	84.55%	83.74%	83.12%
Selling, General & Admin	$14.93M	$11.70M	$10.39M
YoY Change	51.88%	64.32%	52.35%
% of Gross Profit	102.08%	91.85%	98.33%
Research & Development	$4.560M	$3.058M	$2.704M
YoY Change	44.3%	101.85%	105.32%
% of Gross Profit	31.18%	24.0%	25.58%
Depreciation & Amortization	$160.0K	$119.0K	$102.0K
YoY Change	60.0%	30.77%	18.6%
% of Gross Profit	1.09%	0.93%	0.97%
Operating Expenses	$17.66M	$14.76M	$13.10M
YoY Change	35.74%	70.91%	60.92%
Operating Profit	-$3.034M	-$3.901M	-$645.0K
YoY Change	-216.07%	-188.08%	-206.09%
Interest Expense	-$380.0K	$706.0K	$769.0K
YoY Change	-22.45%	-35.11%	-54.58%
% of Operating Profit
Other Income/Expense, Net	$0.00	$0.00	$0.00
YoY Change		-100.0%	-100.0%
Pretax Income	-$4.810M	-$4.590M	-$1.380M
YoY Change	-325.82%	-178.46%	8.66%
Income Tax	$80.00K	$0.00	$0.00
% Of Pretax Income
Net Earnings	-$4.889M	-$4.589M	-$1.376M
YoY Change	-337.91%	-178.46%	8.43%
Net Earnings / Revenue	-28.26%	-30.16%	-10.82%
Basic Earnings Per Share	-$0.23	-$0.23	-$0.08
Diluted Earnings Per Share	-$0.23	-$0.23	-$0.08
COMMON SHARES
Basic Shares Outstanding	19.91M shares	19.94M shares	17.54M shares
Diluted Shares Outstanding		19.94M shares	17.54M shares

Balance Sheet

Concept	2020 Q4	2020 Q3	2020 Q2
SHORT-TERM ASSETS
Cash & Short-Term Investments	$409.9M	$183.1M	$179.8M
YoY Change	314.88%	93.76%	927.43%
Cash & Equivalents	$409.9M	$183.1M	$179.8M
Short-Term Investments
Other Short-Term Assets	$4.800M	$3.700M	$1.700M
YoY Change	140.0%	68.18%	112.5%
Inventory	$2.217M	$1.679M	$1.667M
Prepaid Expenses
Receivables	$12.76M	$12.62M	$12.53M
Other Receivables	$0.00	$0.00	$0.00
Total Short-Term Assets	$429.6M	$201.1M	$195.7M
YoY Change	268.18%	83.01%	585.97%
LONG-TERM ASSETS
Property, Plant & Equipment	$7.102M	$6.646M	$5.024M
YoY Change	244.76%	269.58%	188.21%
Goodwill
YoY Change
Intangibles
YoY Change
Long-Term Investments
YoY Change
Other Assets	$1.536M	$1.638M	$199.0K
YoY Change	1037.78%	1779.13%	-89.03%
Total Long-Term Assets	$9.734M	$9.329M	$5.875M
YoY Change	217.59%	179.54%	21.82%
TOTAL ASSETS
Total Short-Term Assets	$429.6M	$201.1M	$195.7M
Total Long-Term Assets	$9.734M	$9.329M	$5.875M
Total Assets	$439.3M	$210.4M	$201.5M
YoY Change	266.88%	85.86%	504.39%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$2.098M	$2.101M	$2.495M
YoY Change	12.49%	67.91%	19.67%
Accrued Expenses	$12.10M	$9.800M	$7.300M
YoY Change	61.33%	113.04%	65.91%
Deferred Revenue	$6.615M	$8.350M	$8.350M
YoY Change
Short-Term Debt	$0.00	$0.00	$0.00
YoY Change			-100.0%
Long-Term Debt Due	$0.00	$10.00M	$10.00M
YoY Change	-100.0%	200.0%	1100.0%
Total Short-Term Liabilities	$20.88M	$30.24M	$28.24M
YoY Change	36.54%	227.35%	140.45%
LONG-TERM LIABILITIES
Long-Term Debt	$0.00	$12.46M	$14.74M
YoY Change	-100.0%	-42.26%	-38.22%
Other Long-Term Liabilities	$1.026M	$1.100M	$900.0K
YoY Change	926.0%	1000.0%	-30.77%
Total Long-Term Liabilities	$1.026M	$12.46M	$14.74M
YoY Change	-94.68%	-42.26%	-38.22%
TOTAL LIABILITIES
Total Short-Term Liabilities	$20.88M	$30.24M	$28.24M
Total Long-Term Liabilities	$1.026M	$12.46M	$14.74M
Total Liabilities	$23.64M	$43.84M	$43.92M
YoY Change	-31.75%	42.03%	18.9%
SHAREHOLDERS EQUITY
Retained Earnings	-$62.50M	-$57.61M	-$53.02M
YoY Change	19.7%	6.09%	-11.78%
Common Stock
YoY Change
Preferred Stock
YoY Change
Treasury Stock (at cost)
YoY Change
Treasury Stock Shares
Shareholders Equity	$415.7M	$166.6M	$157.6M
YoY Change
Total Liabilities & Shareholders Equity	$439.3M	$210.4M	$201.5M
YoY Change	266.88%	85.86%	504.39%

Cashflow Statement

Concept	2020 Q4	2020 Q3	2020 Q2
OPERATING ACTIVITIES
Net Income	-$4.889M	-$4.589M	-$1.376M
YoY Change	-337.91%	-178.46%	8.43%
Depreciation, Depletion And Amortization	$160.0K	$119.0K	$102.0K
YoY Change	60.0%	30.77%	18.6%
Cash From Operating Activities	-$430.0K	-$2.950M	$13.50M
YoY Change	-109.56%	-493.33%	2712.5%
INVESTING ACTIVITIES
Capital Expenditures	-$590.0K	-$1.900M	-$1.760M
YoY Change	68.57%	1017.65%	877.78%
Acquisitions
YoY Change
Other Investing Activities	$0.00	$0.00
YoY Change
Cash From Investing Activities	-$590.0K	-$1.900M	-$1.760M
YoY Change	68.57%	1017.65%	877.78%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	227.8M	8.150M	69.36M
YoY Change	98952.17%	-89.34%	7358.06%
NET CHANGE
Cash From Operating Activities	-430.0K	-2.950M	13.50M
Cash From Investing Activities	-590.0K	-1.900M	-1.760M
Cash From Financing Activities	227.8M	8.150M	69.36M
Net Change In Cash	226.8M	3.300M	81.10M
YoY Change	5078.08%	-95.71%	6493.5%
FREE CASH FLOW
Cash From Operating Activities	-$430.0K	-$2.950M	$13.50M
Capital Expenditures	-$590.0K	-$1.900M	-$1.760M
Free Cash Flow	$160.0K	-$1.050M	$15.26M
YoY Change	-96.7%	-214.13%	2212.12%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2020	dei	Entity Central Index Key EntityCentralIndexKey	0001447362
CY2020	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2020
CY2020	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	FY
CY2020	dei	Amendment Flag AmendmentFlag	false
CY2019Q3	us-gaap	Stockholders Equity Note Stock Split Conversion Ratio1 StockholdersEquityNoteStockSplitConversionRatio1	0.8203
CY2019Q3	us-gaap	Stockholders Equity Note Stock Split Conversion Ratio1 StockholdersEquityNoteStockSplitConversionRatio1	0.8203
CY2020	dei	Document Type DocumentType	10-K
CY2020	dei	Document Type DocumentType	10-K
CY2020	dei	Document Annual Report DocumentAnnualReport	true
CY2020	dei	Document Period End Date DocumentPeriodEndDate	2020-12-31
CY2020	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2020	dei	Entity Registrant Name EntityRegistrantName	CASTLE BIOSCIENCES, INC.
CY2020	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	DE
CY2020	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	77-0701774
CY2020	dei	Document Transition Report DocumentTransitionReport	false
CY2020	dei	Entity File Number EntityFileNumber	001-38984
CY2020	dei	Entity Address Address Line1 EntityAddressAddressLine1	820 S. Friendswood Drive
CY2020	dei	Entity Address Address Line2 EntityAddressAddressLine2	Suite 201
CY2020	dei	Entity Address City Or Town EntityAddressCityOrTown	Friendswood
CY2020	dei	Entity Address State Or Province EntityAddressStateOrProvince	TX
CY2020	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	77546
CY2020	dei	City Area Code CityAreaCode	866
CY2020	dei	Local Phone Number LocalPhoneNumber	788-9007
CY2020	dei	Security12b Title Security12bTitle	Common Stock, $0.001 par value per share
CY2020	dei	Trading Symbol TradingSymbol	CSTL
CY2020	dei	Security Exchange Name SecurityExchangeName	NASDAQ
CY2020	dei	Entity Well Known Seasoned Issuer EntityWellKnownSeasonedIssuer	Yes
CY2020	dei	Entity Voluntary Filers EntityVoluntaryFilers	No
CY2019Q4	us-gaap	Inventory Net InventoryNet	1237000	USD
CY2020	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
CY2020	dei	Entity Interactive Data Current EntityInteractiveDataCurrent	Yes
CY2020	dei	Entity Filer Category EntityFilerCategory	Non-accelerated Filer
CY2020	dei	Entity Small Business EntitySmallBusiness	true
CY2020	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	true
CY2020	dei	Entity Ex Transition Period EntityExTransitionPeriod	false
CY2020	dei	Icfr Auditor Attestation Flag IcfrAuditorAttestationFlag	false
CY2020	dei	Entity Shell Company EntityShellCompany	false
CY2020Q2	dei	Entity Public Float EntityPublicFloat	518900000	USD
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CY2020	us-gaap	Share Based Compensation ShareBasedCompensation	8309000	USD
CY2019	us-gaap	Share Based Compensation ShareBasedCompensation	1249000	USD
CY2020	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	0	USD
CY2019	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	4000	USD
CY2019	us-gaap	Defined Contribution Plan Employer Discretionary Contribution Amount DefinedContributionPlanEmployerDiscretionaryContributionAmount	434000	USD
CY2020	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	839000	USD
CY2020Q2	cstl	Other Operating Income Loss Cares Act OtherOperatingIncomeLossCARESAct	1900000	USD
CY2019	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	1925000	USD
CY2020	cstl	Other Non Cash Interest OtherNonCashInterest	0	USD
CY2019	cstl	Other Non Cash Interest OtherNonCashInterest	442000	USD
CY2020	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	-1397000	USD
CY2019	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	5213000	USD
CY2020	us-gaap	Fair Value Adjustment Of Warrants FairValueAdjustmentOfWarrants	0	USD
CY2019	us-gaap	Fair Value Adjustment Of Warrants FairValueAdjustmentOfWarrants	619000	USD
CY2020	us-gaap	Embedded Derivative Gain Loss On Embedded Derivative Net EmbeddedDerivativeGainLossOnEmbeddedDerivativeNet	0	USD
CY2019	us-gaap	Embedded Derivative Gain Loss On Embedded Derivative Net EmbeddedDerivativeGainLossOnEmbeddedDerivativeNet	-237000	USD
CY2020	us-gaap	Fair Value Option Changes In Fair Value Gain Loss1 FairValueOptionChangesInFairValueGainLoss1	0	USD
CY2019	us-gaap	Fair Value Option Changes In Fair Value Gain Loss1 FairValueOptionChangesInFairValueGainLoss1	-2077000	USD
CY2020	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	16000	USD
CY2019	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	0	USD
CY2020	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	-1663000	USD
CY2019	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	896000	USD
CY2020	us-gaap	Increase Decrease In Prepaid Deferred Expense And Other Assets IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	2815000	USD
CY2019	us-gaap	Increase Decrease In Prepaid Deferred Expense And Other Assets IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	1276000	USD
CY2020	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	980000	USD
CY2019	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	355000	USD
CY2020	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	1401000	USD
CY2019	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	85000	USD
CY2020	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	169000	USD
CY2019	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	557000	USD
CY2020	us-gaap	Increase Decrease In Employee Related Liabilities IncreaseDecreaseInEmployeeRelatedLiabilities	3329000	USD
CY2019	us-gaap	Increase Decrease In Employee Related Liabilities IncreaseDecreaseInEmployeeRelatedLiabilities	1208000	USD
CY2020	us-gaap	Increase Decrease In Contract With Customer Liability IncreaseDecreaseInContractWithCustomerLiability	8350000	USD
CY2019	us-gaap	Increase Decrease In Contract With Customer Liability IncreaseDecreaseInContractWithCustomerLiability	0	USD
CY2020	us-gaap	Increase Decrease In Other Accrued Liabilities IncreaseDecreaseInOtherAccruedLiabilities	561000	USD
CY2019	us-gaap	Increase Decrease In Other Accrued Liabilities IncreaseDecreaseInOtherAccruedLiabilities	879000	USD
CY2020	cstl	Increase Decreasein Deferred Lease Liability IncreaseDecreaseinDeferredLeaseLiability	272000	USD
CY2019	cstl	Increase Decreasein Deferred Lease Liability IncreaseDecreaseinDeferredLeaseLiability	12000	USD
CY2020	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	9865000	USD
CY2019	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	7015000	USD
CY2020	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	4751000	USD
CY2019	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	937000	USD
CY2020	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	3000	USD
CY2019	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	0	USD
CY2020	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-4748000	USD
CY2019	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-937000	USD
CY2020	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	330041000	USD
CY2019	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	65931000	USD
CY2020	us-gaap	Proceeds From Warrant Exercises ProceedsFromWarrantExercises	0	USD
CY2019	us-gaap	Proceeds From Warrant Exercises ProceedsFromWarrantExercises	49000	USD
CY2020	us-gaap	Proceeds From Related Party Debt ProceedsFromRelatedPartyDebt	4756000	USD
CY2020	us-gaap	Proceeds From Short Term Debt ProceedsFromShortTermDebt	0	USD
CY2019	us-gaap	Proceeds From Short Term Debt ProceedsFromShortTermDebt	11695000	USD
CY2020	cstl	Proceeds From Issuance Of Convertible Debt And Common Stock Warrants Net Of Issuance Costs ProceedsFromIssuanceOfConvertibleDebtAndCommonStockWarrantsNetOfIssuanceCosts	0	USD
CY2019	cstl	Proceeds From Issuance Of Convertible Debt And Common Stock Warrants Net Of Issuance Costs ProceedsFromIssuanceOfConvertibleDebtAndCommonStockWarrantsNetOfIssuanceCosts	9236000	USD
CY2020	us-gaap	Proceeds From Issuance Of Secured Debt ProceedsFromIssuanceOfSecuredDebt	0	USD
CY2019	us-gaap	Proceeds From Issuance Of Secured Debt ProceedsFromIssuanceOfSecuredDebt	1776000	USD
CY2020	us-gaap	Repayments Of Secured Debt RepaymentsOfSecuredDebt	27359000	USD
CY2019	us-gaap	Repayments Of Secured Debt RepaymentsOfSecuredDebt	0	USD
CY2020	us-gaap	Repayments Of Long Term Lines Of Credit RepaymentsOfLongTermLinesOfCredit	0	USD
CY2019	us-gaap	Repayments Of Long Term Lines Of Credit RepaymentsOfLongTermLinesOfCredit	1791000	USD
CY2020	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	1593000	USD
CY2019	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	1174000	USD
CY2020	us-gaap	Proceeds From Stock Plans ProceedsFromStockPlans	1615000	USD
CY2019	us-gaap	Proceeds From Stock Plans ProceedsFromStockPlans	218000	USD
CY2020	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	305890000	USD
CY2019	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	88288000	USD
CY2020	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	311007000	USD
CY2019	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	94366000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	98845000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	4479000	USD
CY2020Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	409852000	USD
CY2020	cstl	Contract With Customer Customer Payment Terms ContractWithCustomerCustomerPaymentTerms	P30D
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	98845000	USD
CY2020	us-gaap	Interest Paid Net InterestPaidNet	1978000	USD
CY2019	us-gaap	Interest Paid Net InterestPaidNet	2206000	USD
CY2020	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	102000	USD
CY2019	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	-150000	USD
CY2020	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	58000	USD
CY2019	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	7000	USD
CY2020	cstl	Property And Equipment Acquired With Tenant Improvement Allowance PropertyAndEquipmentAcquiredWithTenantImprovementAllowance	714000	USD
CY2019	cstl	Property And Equipment Acquired With Tenant Improvement Allowance PropertyAndEquipmentAcquiredWithTenantImprovementAllowance	0	USD
CY2020	cstl	Offering Costs Incurred But Not Yet Paid OfferingCostsIncurredButNotYetPaid	377000	USD
CY2019	cstl	Offering Costs Incurred But Not Yet Paid OfferingCostsIncurredButNotYetPaid	0	USD
CY2020	us-gaap	Conversion Of Stock Amount Issued1 ConversionOfStockAmountIssued1	0	USD
CY2019	us-gaap	Conversion Of Stock Amount Issued1 ConversionOfStockAmountIssued1	46743000	USD
CY2020	cstl	Conversion Of Preferred Stock Warrants Amount Issued ConversionOfPreferredStockWarrantsAmountIssued	0	USD
CY2019	cstl	Conversion Of Preferred Stock Warrants Amount Issued ConversionOfPreferredStockWarrantsAmountIssued	1744000	USD
CY2020	us-gaap	Debt Conversion Converted Instrument Amount1 DebtConversionConvertedInstrumentAmount1	0	USD
CY2019	us-gaap	Debt Conversion Converted Instrument Amount1 DebtConversionConvertedInstrumentAmount1	26577000	USD
CY2020	us-gaap	Contract With Customer Performance Obligation Satisfied In Previous Period ContractWithCustomerPerformanceObligationSatisfiedInPreviousPeriod	176000	USD
CY2020	cstl	Exercise Of Common Stock Warrants Noncash ExerciseOfCommonStockWarrantsNoncash	250000	USD
CY2019	cstl	Exercise Of Common Stock Warrants Noncash ExerciseOfCommonStockWarrantsNoncash	455000	USD
CY2020Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	409900000	USD
CY2020	us-gaap	Use Of Estimates UseOfEstimates	The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Significant items subject to such estimates include revenue recognition, the valuation of stock-based compensation, assessing future tax exposure and the realization of deferred tax assets, the useful lives and recoverability of property and equipment, and contingent liabilities. The Company bases these estimates on historical and anticipated results, trends, and various other assumptions that the Company believes are reasonable under the circumstances, including assumptions as to future events. These estimates form the basis for making judgments about the carrying values of assets and liabilities and recorded revenues and expenses that are not readily apparent from other sources. Actual results could differ from those estimates and assumptions. The Company has considered the potential impact of the COVID-19 pandemic on its estimates and assumptions. The extent to which the COVID-19 pandemic may impact the Company’s estimates in future periods is uncertain and subject to change.
CY2020	us-gaap	Number Of Operating Segments NumberOfOperatingSegments	1	segment
CY2020	us-gaap	Concentration Risk Credit Risk ConcentrationRiskCreditRisk	Cash deposits at financial institutions may exceed the amount of insurance provided by the FDIC. Management believes that the Company is not exposed to significant credit risk on its cash deposits due to the financial position of the institutions in which deposits are held. The Company has not experienced any losses on its cash or cash equivalents.
CY2020Q4	us-gaap	Allowance For Doubtful Accounts Receivable AllowanceForDoubtfulAccountsReceivable	0	USD
CY2019Q4	us-gaap	Allowance For Doubtful Accounts Receivable AllowanceForDoubtfulAccountsReceivable	0	USD
CY2020Q4	cstl	Other Operating Income Loss Cares Act OtherOperatingIncomeLossCARESAct	1900000	USD
CY2020Q4	us-gaap	Accrued Bonuses Current And Noncurrent AccruedBonusesCurrentAndNoncurrent	7175000	USD
CY2019Q4	us-gaap	Accrued Bonuses Current And Noncurrent AccruedBonusesCurrentAndNoncurrent	4785000	USD
CY2020	us-gaap	Defined Contribution Plan Employer Discretionary Contribution Amount DefinedContributionPlanEmployerDiscretionaryContributionAmount	789000	USD
CY2020Q4	cstl	Deferred Payroll Taxes Cares Act DeferredPayrollTaxesCARESAct	551000	USD
CY2020Q2	us-gaap	Stock Issued During Period Shares New Issues StockIssuedDuringPeriodSharesNewIssues	2000000	shares
CY2020Q3	us-gaap	Stock Issued During Period Shares New Issues StockIssuedDuringPeriodSharesNewIssues	300000	shares
CY2020Q4	us-gaap	Stock Issued During Period Shares New Issues StockIssuedDuringPeriodSharesNewIssues	4600000	shares
CY2020	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	-10284000	USD
CY2019	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	2991000	USD
CY2020	us-gaap	Dilutive Securities Effect On Basic Earnings Per Share Other DilutiveSecuritiesEffectOnBasicEarningsPerShareOther	0	USD
CY2019	us-gaap	Dilutive Securities Effect On Basic Earnings Per Share Other DilutiveSecuritiesEffectOnBasicEarningsPerShareOther	5213000	USD
CY2020	us-gaap	Interest On Convertible Debt Net Of Tax InterestOnConvertibleDebtNetOfTax	0	USD
CY2019	us-gaap	Interest On Convertible Debt Net Of Tax InterestOnConvertibleDebtNetOfTax	420000	USD
CY2020	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	-10284000	USD
CY2019	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	-1802000	USD
CY2020	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	18929000	shares
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	8584000	shares
CY2020	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	0	shares
CY2019	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	74000	shares
CY2020	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	18929000	shares
CY2019	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	8658000	shares
CY2020	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.54
CY2019	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.35
CY2020	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.54
CY2019	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.21
CY2020	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	2924000	shares
CY2019	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	6677000	shares
CY2020Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	8756000	USD
CY2019Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	3263000	USD
CY2020Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	1654000	USD
CY2019Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	1203000	USD
CY2020Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	7102000	USD
CY2019Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	2060000	USD
CY2020	us-gaap	Depreciation Depreciation	472000	USD
CY2019	us-gaap	Depreciation Depreciation	354000	USD
CY2020Q4	us-gaap	Accrued Professional Fees Current AccruedProfessionalFeesCurrent	1891000	USD
CY2019Q4	us-gaap	Accrued Professional Fees Current AccruedProfessionalFeesCurrent	1162000	USD
CY2020Q4	us-gaap	Accrued Employee Benefits Current And Noncurrent AccruedEmployeeBenefitsCurrentAndNoncurrent	536000	USD
CY2019Q4	us-gaap	Accrued Employee Benefits Current And Noncurrent AccruedEmployeeBenefitsCurrentAndNoncurrent	218000	USD
CY2020Q4	us-gaap	Accrued Payroll Taxes Current AccruedPayrollTaxesCurrent	276000	USD
CY2019Q4	us-gaap	Accrued Payroll Taxes Current AccruedPayrollTaxesCurrent	0	USD
CY2020Q4	us-gaap	Accrued Royalties Current AccruedRoyaltiesCurrent	151000	USD
CY2019Q4	us-gaap	Accrued Royalties Current AccruedRoyaltiesCurrent	169000	USD
CY2020Q4	us-gaap	Accrued Income Taxes Current AccruedIncomeTaxesCurrent	62000	USD
CY2019Q4	us-gaap	Accrued Income Taxes Current AccruedIncomeTaxesCurrent	79000	USD
CY2020Q4	us-gaap	Interest Payable Current InterestPayableCurrent	0	USD
CY2019Q4	us-gaap	Interest Payable Current InterestPayableCurrent	184000	USD
CY2020Q4	us-gaap	Other Sundry Liabilities Current OtherSundryLiabilitiesCurrent	139000	USD
CY2019Q4	us-gaap	Other Sundry Liabilities Current OtherSundryLiabilitiesCurrent	0	USD
CY2020Q4	us-gaap	Other Accrued Liabilities Current OtherAccruedLiabilitiesCurrent	3055000	USD
CY2019Q4	us-gaap	Other Accrued Liabilities Current OtherAccruedLiabilitiesCurrent	1812000	USD
CY2020Q4	us-gaap	Operating Leases Future Minimum Payments Due Current OperatingLeasesFutureMinimumPaymentsDueCurrent	1164000	USD
CY2020Q4	us-gaap	Operating Leases Future Minimum Payments Due In Two Years OperatingLeasesFutureMinimumPaymentsDueInTwoYears	1148000	USD
CY2020Q4	us-gaap	Operating Leases Future Minimum Payments Due In Three Years OperatingLeasesFutureMinimumPaymentsDueInThreeYears	1142000	USD
CY2020Q4	us-gaap	Operating Leases Future Minimum Payments Due In Four Years OperatingLeasesFutureMinimumPaymentsDueInFourYears	1154000	USD
CY2020Q4	us-gaap	Operating Leases Future Minimum Payments Due In Five Years OperatingLeasesFutureMinimumPaymentsDueInFiveYears	1119000	USD
CY2020Q4	us-gaap	Operating Leases Future Minimum Payments Due Thereafter OperatingLeasesFutureMinimumPaymentsDueThereafter	1037000	USD
CY2020Q4	us-gaap	Operating Leases Future Minimum Payments Due OperatingLeasesFutureMinimumPaymentsDue	6764000	USD
CY2020	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	548000	USD
CY2019	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	395000	USD
CY2019Q3	cstl	Class Of Warrant Or Right Conversion Multiplier ClassOfWarrantOrRightConversionMultiplier	1.219
CY2019Q3	cstl	Temporary Equity Conversion Multiplier TemporaryEquityConversionMultiplier	1.219
CY2019Q3	us-gaap	Temporary Equity Shares Outstanding TemporaryEquitySharesOutstanding	9973884	shares
CY2019Q3	cstl	Class Of Warrant Or Right Conversion Multiplier ClassOfWarrantOrRightConversionMultiplier	1.219
CY2019Q3	cstl	Class Of Warrant Or Right Conversion Multiplier ClassOfWarrantOrRightConversionMultiplier	1.219
CY2020Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	200000000	shares
CY2020Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	0.001
CY2019Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	0.001
CY2020Q4	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	10000000	shares
CY2020Q4	us-gaap	Preferred Stock Par Or Stated Value Per Share PreferredStockParOrStatedValuePerShare	0.001
CY2019	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0
CY2020	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0
CY2019	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0
CY2020	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0
CY2019Q3	us-gaap	Proceeds From Issuance Initial Public Offering ProceedsFromIssuanceInitialPublicOffering	65900000	USD
CY2020	cstl	Offering Costs Incurred But Not Yet Paid OfferingCostsIncurredButNotYetPaid	400000	USD
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	1659596	shares
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	1.99
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	1711325	shares
CY2019	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice	19.41
CY2019	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	693127	shares
CY2019	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	1.70
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod	39828	shares
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice	6.36
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	2637966	shares
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	13.30
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	1286065	shares
CY2020	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice	49.63
CY2020	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	460207	shares
CY2020	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	3.53
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod	94322	shares
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice	27.51
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	3369502	shares
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	28.11
CY2020	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	P8Y8M19D
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue	131525000	USD
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber	824128	shares
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice	10.67
CY2020	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Weighted Average Remaining Contractual Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1	P7Y6M14D
CY2020Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Intrinsic Value1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1	46546000	USD
CY2020Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Number Of Shares SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares	68150	shares
CY2020Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Weighted Average Grant Date Fair Value SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue	2.39
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	0
CY2020	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	8309000	USD
CY2019	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	1249000	USD
CY2020Q4	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Stock Options EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions	57120000	USD
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CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	5151000	USD
CY2020	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	0	USD
CY2019	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	0	USD
CY2020	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	0	USD
CY2019	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	0	USD
CY2020	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	84000	USD
CY2019	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	72000	USD
CY2020	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	84000	USD
CY2019	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	72000	USD
CY2020	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	0	USD
CY2019	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	0	USD
CY2020	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	0	USD
CY2019	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	0	USD
CY2020	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	0	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	0	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	84000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	72000	USD
CY2020	us-gaap	Income Loss Attributable To Parent IncomeLossAttributableToParent	-10200000	USD
CY2019	us-gaap	Income Loss Attributable To Parent IncomeLossAttributableToParent	5349000	USD
CY2020	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	-2142000	USD
CY2019	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	1123000	USD
CY2020	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	-311000	USD
CY2019	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	958000	USD
CY2020	cstl	Effective Income Tax Rate Reconciliation Mark To Market Losses Amount EffectiveIncomeTaxRateReconciliationMarkToMarketLossesAmount	0	USD
CY2019	cstl	Effective Income Tax Rate Reconciliation Mark To Market Losses Amount EffectiveIncomeTaxRateReconciliationMarkToMarketLossesAmount	566000	USD
CY2020	us-gaap	Income Tax Reconciliation Nondeductible Expense Meals And Entertainment IncomeTaxReconciliationNondeductibleExpenseMealsAndEntertainment	235000	USD
CY2019	us-gaap	Income Tax Reconciliation Nondeductible Expense Meals And Entertainment IncomeTaxReconciliationNondeductibleExpenseMealsAndEntertainment	224000	USD
CY2020	cstl	Effective Income Tax Rate Reconciliation Convertible Debt Interest Amount EffectiveIncomeTaxRateReconciliationConvertibleDebtInterestAmount	0	USD
CY2019	cstl	Effective Income Tax Rate Reconciliation Convertible Debt Interest Amount EffectiveIncomeTaxRateReconciliationConvertibleDebtInterestAmount	95000	USD
CY2020	us-gaap	Income Tax Reconciliation Tax Credits Research IncomeTaxReconciliationTaxCreditsResearch	703000	USD
CY2019	us-gaap	Income Tax Reconciliation Tax Credits Research IncomeTaxReconciliationTaxCreditsResearch	251000	USD
CY2020	us-gaap	Income Tax Reconciliation Change In Deferred Tax Assets Valuation Allowance IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance	2784000	USD
CY2019	us-gaap	Income Tax Reconciliation Change In Deferred Tax Assets Valuation Allowance IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance	-2747000	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Share Based Compensation Excess Tax Benefit Amount EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitAmount	-781000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Share Based Compensation Excess Tax Benefit Amount EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitAmount	65000	USD
CY2020	cstl	Effective Income Tax Rate Reconciliation Nondeductible Expense Officers Compensation Amount EffectiveIncomeTaxRateReconciliationNondeductibleExpenseOfficersCompensationAmount	963000	USD
CY2019	cstl	Effective Income Tax Rate Reconciliation Nondeductible Expense Officers Compensation Amount EffectiveIncomeTaxRateReconciliationNondeductibleExpenseOfficersCompensationAmount	0	USD
CY2020	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	39000	USD
CY2019	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	39000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	84000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	72000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	13720000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	14077000	USD
CY2020Q4	cstl	Deferred Tax Assets Tax Deferred Expense Reservesand Accruals Accounts Payable DeferredTaxAssetsTaxDeferredExpenseReservesandAccrualsAccountsPayable	0	USD
CY2019Q4	cstl	Deferred Tax Assets Tax Deferred Expense Reservesand Accruals Accounts Payable DeferredTaxAssetsTaxDeferredExpenseReservesandAccrualsAccountsPayable	456000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Accrued Liabilities DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities	2730000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Accrued Liabilities DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities	1817000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Credit Carryforwards Research DeferredTaxAssetsTaxCreditCarryforwardsResearch	1777000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Credit Carryforwards Research DeferredTaxAssetsTaxCreditCarryforwardsResearch	993000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Goodwill And Intangible Assets DeferredTaxAssetsGoodwillAndIntangibleAssets	46000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Goodwill And Intangible Assets DeferredTaxAssetsGoodwillAndIntangibleAssets	50000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Share Based Compensation Cost DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost	761000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Share Based Compensation Cost DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost	127000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Charitable Contribution Carryforwards DeferredTaxAssetsCharitableContributionCarryforwards	0	USD
CY2019Q4	us-gaap	Deferred Tax Assets Charitable Contribution Carryforwards DeferredTaxAssetsCharitableContributionCarryforwards	2000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	19034000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	17522000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	15204000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	12420000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	3830000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	5102000	USD
CY2020Q4	cstl	Deferred Tax Liabilities Accounts Receivable DeferredTaxLiabilitiesAccountsReceivable	0	USD
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CY2020Q4	us-gaap	Deferred Tax Liabilities Prepaid Expenses DeferredTaxLiabilitiesPrepaidExpenses	289000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Prepaid Expenses DeferredTaxLiabilitiesPrepaidExpenses	757000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	776000	USD
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CY2019Q4	cstl	Deferred Tax Liabilities Change In Accounting Method DeferredTaxLiabilitiesChangeInAccountingMethod	303000	USD
CY2020Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	3830000	USD
CY2019Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	5102000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	0	USD
CY2019Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	0	USD
CY2020Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	15204000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	12420000	USD
CY2020Q1	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	17418000	USD
CY2020Q2	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	12715000	USD
CY2020Q3	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	15217000	USD
CY2020Q4	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	17299000	USD
CY2020	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	62649000	USD
CY2020Q1	us-gaap	Gross Profit GrossProfit	15027000	USD
CY2020Q2	us-gaap	Gross Profit GrossProfit	10569000	USD
CY2020Q3	us-gaap	Gross Profit GrossProfit	12742000	USD
CY2020Q4	us-gaap	Gross Profit GrossProfit	14626000	USD
CY2020	us-gaap	Gross Profit GrossProfit	52964000	USD
CY2020Q1	us-gaap	Net Income Loss NetIncomeLoss	570000	USD
CY2020Q2	us-gaap	Net Income Loss NetIncomeLoss	-1376000	USD
CY2020Q3	us-gaap	Net Income Loss NetIncomeLoss	-4589000	USD
CY2020Q4	us-gaap	Net Income Loss NetIncomeLoss	-4889000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	-10284000	USD
CY2020Q1	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	570000	USD
CY2020Q2	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	-1376000	USD
CY2020Q3	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	-4589000	USD
CY2020Q4	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	-4889000	USD
CY2020	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	-10284000	USD
CY2020Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.03
CY2020Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.08
CY2020Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.23
CY2020Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.23
CY2020	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.54
CY2020Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.03
CY2020Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.08
CY2020Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.23
CY2020Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.23
CY2020	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.54
CY2019Q1	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	8717000	USD
CY2019Q2	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	10739000	USD
CY2019Q3	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	14774000	USD
CY2019Q4	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	17635000	USD
CY2019	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	51865000	USD
CY2019Q1	us-gaap	Gross Profit GrossProfit	7119000	USD
CY2019Q2	us-gaap	Gross Profit GrossProfit	8746000	USD
CY2019Q3	us-gaap	Gross Profit GrossProfit	13066000	USD
CY2019Q4	us-gaap	Gross Profit GrossProfit	15624000	USD
CY2019	us-gaap	Gross Profit GrossProfit	44555000	USD
CY2019Q1	us-gaap	Net Income Loss NetIncomeLoss	-1358000	USD
CY2019Q2	us-gaap	Net Income Loss NetIncomeLoss	-1269000	USD
CY2019Q3	us-gaap	Net Income Loss NetIncomeLoss	5849000	USD
CY2019Q4	us-gaap	Net Income Loss NetIncomeLoss	2055000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	5277000	USD
CY2019Q1	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	-2342000	USD
CY2019Q2	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	-2265000	USD
CY2019Q3	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	5543000	USD
CY2019Q4	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	2055000	USD
CY2019	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	2991000	USD
CY2019Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-1.22
CY2019Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-1.05
CY2019Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.43
CY2019Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.12
CY2019	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.35
CY2019Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-1.22
CY2019Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-1.05
CY2019Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.05
CY2019Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.11
CY2019	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.21
CY2020Q2	cstl	Other Operating Income Loss Cares Act OtherOperatingIncomeLossCARESAct	1900000	USD
CY2020Q3	cstl	Other Operating Income Loss Cares Act OtherOperatingIncomeLossCARESAct	-1900000	USD
CY2020Q4	cstl	Other Operating Income Loss Cares Act OtherOperatingIncomeLossCARESAct	1900000	USD
CY2020Q4	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	-1400000	USD
CY2019Q3	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	5200000	USD

Files In Submission

Name	View Source	Status
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0001447362-21-000047-index.html	Edgar Link	pending
0001447362-21-000047.txt	Edgar Link	pending
0001447362-21-000047-xbrl.zip	Edgar Link	pending
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cstl-20201231_htm.xml	Edgar Link	completed
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cstl-20201231_pre.xml	Edgar Link	unprocessable
exhibit1011-nonxemployeedi.htm	Edgar Link	pending
exhibit1023-firstamendment.htm	Edgar Link	pending
exhibit23consent10-k2020.htm	Edgar Link	pending
exhibit311yearend2020.htm	Edgar Link	pending
exhibit312yearend2020.htm	Edgar Link	pending
exhibit321yearend2020.htm	Edgar Link	pending
exhibit322yearend2020.htm	Edgar Link	pending
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$CSTL
CASTLE BIOSCIENCES INC Stock $cstl

2020 Q4 Form 10-K Financial Statement

#000144736221000047 Filed on March 11, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$CSTL CASTLE BIOSCIENCES INC Stock $cstl

2020 Q4 Form 10-K Financial Statement

#000144736221000047 Filed on March 11, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$CSTL
CASTLE BIOSCIENCES INC Stock $cstl