XML 81 R55.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Non-Controlling Interests - Spero Europe - Additional Information (Detail) - USD ($) | 1 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Jan. 31, 2016 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | May 31, 2017
Noncontrolling Interest [Line Items] |  |  |  |  |
Research and development expense |  | $ 32,869,000 | $ 26,333,000 | $ 11,125,000 |
Non-controlling interest |  | 355,000 | $ (3,808,000) |  |
Spero Europe, Ltd. [Member] |  |  |  |  |
Noncontrolling Interest [Line Items] |  |  |  |  |
Ownership percentage |  |  | 5.00% |  |
Termination of agreement notice period | 30 days |  |  |  |
Non-controlling interest |  | $ 0 | $ (21,000) |  |
Spero Europe, Ltd. [Member] | Maximum [Member] |  |  |  |  |
Noncontrolling Interest [Line Items] |  |  |  |  |
Non-controlling interest |  |  |  |  | $ 100,000
Spero Europe, Ltd. [Member] | Licensing Agreements [Member] | Anti- dilution Rights [Member] |  |  |  |  |
Noncontrolling Interest [Line Items] |  |  |  |  |
Research and development expense | $ 200,000 |  |  |  |
Spero Europe, Ltd. [Member] | Promiliad Biopharma, Inc. [Member] |  |  |  |  |
Noncontrolling Interest [Line Items] |  |  |  |  |
Ownership percentage | 5.00% |  |  |  |
Common stock issued, aggregate fair value | $ 100,000 |  |  |  |
Milestone payments | 4,100,000 |  |  |  |
Proceeds from the issuance of common stock, net of issuance costs | 0 |  |  |  |
Maximum amounts of investments for anti-dilution protection | $ 5,000,000 |  |  |  |
Spero Europe, Ltd. [Member] | Promiliad Biopharma, Inc. [Member] | Anti- dilution Rights [Member] |  |  |  |  |
Noncontrolling Interest [Line Items] |  |  |  |  |
Ownership percentage | 5.00% |  |  |  |
Spero Europe, Ltd. [Member] | Promiliad Biopharma, Inc. [Member] | Licensing Agreements [Member] |  |  |  |  |
Noncontrolling Interest [Line Items] |  |  |  |  |
Research and development expense | $ 100,000 |  |  |  |

X
- Definition Maximum amounts of investments by parent that would trigger the anti-dilution protection. + References No definition available. + Details
Name: | spro_MaximumInvestmentAmountTriggeringAdditionalShareIssuance
Namespace Prefix: | spro_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Milestone payments. + References No definition available. + Details
Name: | spro_MilestonePayments
Namespace Prefix: | spro_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Termination of agreement notice period. + References No definition available. + Details
Name: | spro_TerminationOfAgreementNoticePeriod
Namespace Prefix: | spro_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which is directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent (that is, noncontrolling interest, previously referred to as minority interest). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(22)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(24)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.31) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_MinorityInterest
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- 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_MinorityInterestLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
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 inflow from the additional capital contribution to the entity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3255-108585 + Details
Name: | us-gaap_ProceedsFromIssuanceOfCommonStock
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 730 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6420194&loc=d3e21568-108373 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 985 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6501960&loc=d3e128462-111756 + Details
Name: | us-gaap_ResearchAndDevelopmentExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Equity impact of the value of new stock issued during the period. Includes shares issued in an initial public offering or a secondary public offering. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(28)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21463-112644 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_StockIssuedDuringPeriodValueNewIssues
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_LicensingAgreementsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByLiabilityClassAxis=spro_AntiDilutionRightsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=spro_PromiliadBiopharmaIncMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |