Convertible Notes - Estimated Fair Values (Details) - Compounded Bifurcated Derivatives - Binomial Lattice Model - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Calculated aggregate value	$ 2,870	$ 3,136
Closing price per share of common stock (usd per share)	$ 2.36	$ 3.20
Contractual interest rate	4.00%	4.00%
Volume-weighted average conversion rate (usd per share)	$ 17.04667	$ 17.04667
Contractual remaining term
Debt Instrument [Line Items]
Contractual remaining term	7 years 11 months	8 years 8 months
Risk-free interest rate \| Minimum
Debt Instrument [Line Items]
Derivative liability, measurement input	0.0212	0.0128
Risk-free interest rate \| Maximum
Debt Instrument [Line Items]
Derivative liability, measurement input	0.0305	0.024
Dividend yield
Debt Instrument [Line Items]
Derivative liability, measurement input	0	0
Credit Spread
Debt Instrument [Line Items]
Derivative liability, measurement input	0.2711	0.3698
Volatility
Debt Instrument [Line Items]
Derivative liability, measurement input	0.915	0.990

Closing price per share of common stock.

No definition available.

Name:	fcsc_ClosingPricePerShareOfCommonStock
Namespace Prefix:	fcsc_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Derivative Liability, Term

+ References

No definition available.

+ Details

Name:	fcsc_DerivativeLiabilityTerm
Namespace Prefix:	fcsc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair Value Assumptions, Volume-weighted Average Conversion Rate

+ References

No definition available.

+ Details

Name:	fcsc_FairValueAssumptionsVolumeweightedAverageConversionRate
Namespace Prefix:	fcsc_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Fixed interest rate related to the interest rate derivative.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeFixedInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13433-108611

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226008-175313

+ Details

Name:	us-gaap_DerivativeLiabilities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Value of input used to measure derivative liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

+ Details

Name:	us-gaap_DerivativeLiabilityMeasurementInput
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_FairValueByLiabilityClassAxis=fcsc_CompoundedBifurcatedDerivativesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ValuationTechniqueAxis=fcsc_BinomialLatticeModelMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputExpectedTermMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputRiskFreeInterestRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputExpectedDividendRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputEntityCreditRiskMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputPriceVolatilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: