XML 32 R6.htm IDEA: XBRL DOCUMENT
v3.8.0.1

CONSOLIDATED STATEMENTS OF BRIDGE UNITS, REDEEMABLE CONVERTIBLE PREFERRED SHARES AND STOCKHOLDERS' EQUITY (DEFICIT) (Parenthetical) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Issuance of tranche rights with preferred units |  | $ 909 | $ 2,401
Payment of offering costs | $ 3,574 |  |
Initial Public Offering [Member] |  |  |
Payment of offering costs | 3,574 |  |
Spero Potentiator, Inc. [Member] |  |  |
Ownership percentage |  |  | 49.90%
Spero Gyrase, Inc. [Member] |  |  |
Ownership percentage |  | 20.00% |
Spero Europe, Ltd. [Member] |  |  |
Ownership percentage |  | 5.00% |
Spero Cantab [Member] |  |  |
Ownership percentage |  | 12.50% |
Class A Preferred Unit [Member] |  |  |
Issuance of tranche rights with preferred units |  |  | $ 1,100
Payment of offering costs |  |  | 170
Class B Preferred Units [Member] |  |  |
Payment of offering costs |  | $ 112 |
Issuance of tranche rights derivative liability with preferred units |  | 909 |
Series C Preferred Stock [Member] |  |  |
Payment of offering costs | $ 176 |  |
Bridge Units [Member] |  |  |
Derivative liability |  |  | 2,307
Contingent prepayment option derivative liability |  | $ 908 |
Bridge Units [Member] | Class A Preferred Unit [Member] |  |  |
Tranche rights derivative liability upon issuance of preferred units |  |  | $ 1,301

X
- Definition Contingent prepayment option derivative liability. + References No definition available. + Details
Name: | spro_ContingentPrepaymentOptionDerivativeLiability
Namespace Prefix: | spro_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Issuance of tranche rights derivative liability with preferred units. + References No definition available. + Details
Name: | spro_IssuanceOfTrancheRightsDerivativeLiabilityWithPreferredUnits
Namespace Prefix: | spro_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Issuance of tranche rights with preferred units. + References No definition available. + Details
Name: | spro_IssuanceOfTrancheRightsWithPreferredUnits
Namespace Prefix: | spro_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Tranche rights derivative liability upon issuance of preferred units. + References No definition available. + Details
Name: | spro_TrancheRightsDerivativeLiabilityUponIssuanceOfPreferredUnits
Namespace Prefix: | spro_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of increase (decrease) of financial instrument classified as a derivative asset (liability) after deduction of derivative liability (asset), measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19279-110258 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPeriodIncreaseDecrease
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | duration

X
- Definition The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity. + References No definition available. + Details
Name: | us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The cash outflow for cost incurred directly with the issuance of an equity security. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3291-108585 + Details
Name: | us-gaap_PaymentsOfStockIssuanceCosts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_SubsidiarySaleOfStockAxis=us-gaap_IPOMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ConsolidatedEntitiesAxis=spro_SperoPotentiatorINCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ConsolidatedEntitiesAxis=spro_SperoGyraseINCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ConsolidatedEntitiesAxis=spro_SperoEuropeLTDMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ConsolidatedEntitiesAxis=spro_SperoCantabMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementClassOfStockAxis=spro_ClassAConvertiblePreferredUnitsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementClassOfStockAxis=spro_ClassBPreferredUnitsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementClassOfStockAxis=us-gaap_SeriesCPreferredStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=spro_BridgeUnitsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |