XML 60 R37.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Nature of the Business and Basis of Presentation - Additional Information (Detail) $ / shares in Units, $ in Thousands |  |  |  | 1 Months Ended | 3 Months Ended | 12 Months Ended
--- | --- | --- | --- | --- | --- | ---
Nov. 14, 2017 USD ($) $ / shares shares | Nov. 06, 2017 USD ($) $ / shares shares | Oct. 20, 2017 | Nov. 30, 2017 USD ($) | Mar. 31, 2018 USD ($) | Dec. 31, 2017 USD ($) | Sep. 30, 2017 USD ($) | Jun. 30, 2017 USD ($) | Mar. 31, 2017 USD ($) | Dec. 31, 2016 USD ($) $ / shares | Sep. 30, 2016 USD ($) | Jun. 30, 2016 USD ($) | Mar. 31, 2016 USD ($) | Dec. 31, 2017 USD ($) shares | Dec. 31, 2016 USD ($) $ / shares | Dec. 31, 2015 USD ($)
Nature Of Business And Basis Of Presentation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business combination exchange ratio |  |  |  |  | 1 |  |  |  |  |  |  |  |  | 1 |  |
Share price | $ / shares |  |  |  |  |  |  |  |  |  | $ 0.001 |  |  |  |  | $ 0.001 |
Net proceeds from issuance of common stock |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 77,749 |  |
Net loss |  |  |  |  | $ 10,644 | $ 13,862 | $ 9,836 | $ 9,169 | $ 5,876 | $ 7,211 | $ 6,316 | $ 6,059 | $ 5,905 | 38,743 | $ 25,491 | $ 10,154
Accumulated deficit |  |  |  |  | $ 107,484 | $ 96,840 |  |  |  | $ 45,440 |  |  |  | $ 96,840 | $ 45,440 |
Entity incorporation month and year |  |  |  |  | 2013-12 |  |  |  |  |  |  |  |  |  |  |
State of incorporation |  |  |  |  | Delaware |  |  |  |  |  |  |  |  |  |  |
Merger date |  |  |  |  | Jun. 30, 2017 |  |  |  |  |  |  |  |  |  |  |
Common Stock [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Nature Of Business And Basis Of Presentation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Reverse stock split ratio |  |  | 0.164544 |  |  |  |  |  |  |  |  |  |  |  |  |
Reverse stock split |  |  | One-for-6.0774 |  |  |  |  |  |  |  |  |  |  |  |  |
Net proceeds from issuance of common stock | $ 6,100 | $ 71,600 |  | $ 74,200 |  |  |  |  |  |  |  |  |  |  |  |
Common Stock [Member] | Initial Public Offering [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Nature Of Business And Basis Of Presentation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Issuance of stock, shares | shares | 471,498 | 5,500,000 |  |  |  |  |  |  |  |  |  |  |  | 5,971,498 |  |
Share price | $ / shares | $ 14.00 | $ 14.00 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net proceeds from issuance of common stock | $ 6,100 | $ 71,600 |  |  |  |  |  |  |  |  |  |  |  |  |  |

X
- Definition State or Country Name where an entity is incorporated + References No definition available. + Details
Name: | dei_EntityIncorporationStateCountryName
Namespace Prefix: | dei_
Data Type: | xbrli:normalizedStringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Business combination exchange ratio. + References No definition available. + Details
Name: | spro_BusinessCombinationExchangeRatio
Namespace Prefix: | spro_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | duration

X
- Definition Entity incorporation month and year. + References No definition available. + Details
Name: | spro_EntityIncorporationMonthAndYear
Namespace Prefix: | spro_
Data Type: | xbrli:gYearMonthItemType
Balance Type: | na
Period Type: | duration

X
- Definition Nature of business and basis of presentation. + References No definition available. + Details
Name: | spro_NatureOfBusinessAndBasisOfPresentationLineItems
Namespace Prefix: | spro_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Date when the business acquisition agreement was executed, in CCYY-MM-DD format. + References No definition available. + Details
Name: | us-gaap_BusinessAcquisitionDateOfAcquisitionAgreement1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition The portion of profit or loss for the period, net of income taxes, which is attributable to the parent. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(22)) -URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(18)) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(20)) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 + Details
Name: | us-gaap_NetIncomeLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The cash inflow associated with the amount received from entity's first offering of stock to the public. + 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_ProceedsFromIssuanceInitialPublicOffering
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The cumulative amount of the reporting entity's undistributed earnings or deficit. + References Reference 1: 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)(23)(a)(4)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 2: 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 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(30)(a)(3)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_RetainedEarningsAccumulatedDeficit
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Per share or per unit amount of equity securities issued. + References No definition available. + Details
Name: | us-gaap_SharesIssuedPricePerShare
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of new stock issued during the period. + 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(29)) -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 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 4: 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 + Details
Name: | us-gaap_StockIssuedDuringPeriodSharesNewIssues
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Ratio applied to the conversion of stock split, for example but not limited to, one share converted to two or two shares converted to one. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SAB TOPIC 4.C) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187143-122770 + Details
Name: | us-gaap_StockholdersEquityNoteStockSplitConversionRatio1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | duration

X
- Definition Description of the reverse stock split arrangement. Also provide the retroactive effect given by the reverse split that occurs after the balance sheet date but before the release of financial statements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SAB Topic 4.C) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187143-122770 + Details
Name: | us-gaap_StockholdersEquityReverseStockSplit
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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

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