XML 57 R47.htm IDEA: XBRL DOCUMENT
v3.22.1

Common Stock Warrants - Additional Information (Detail) - USD ($) |  |  |  | 3 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Mar. 23, 2021 | Nov. 29, 2019 | Nov. 26, 2019 | Mar. 31, 2022 | Mar. 03, 2022 | Dec. 31, 2021 | Nov. 09, 2021 | Nov. 02, 2020 | Apr. 16, 2019
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |
Issued |  |  |  | 766,666 |  |  |  |  |
Class of warrants or rights expiration period (in years) |  |  | 30 days |  |  |  |  |  |
Common stock, par value (in usd per share) |  |  |  | $ 0.001 |  | $ 0.001 |  |  |
Number of Shares of Common Stock Issuable (in shares) |  |  |  | 14,023,726 |  | 13,257,160 |  |  |
Class of Warrant or Right, Additional Exercise Price of Warrants or Rights | $ 0.01 | $ 0.001 |  |  |  |  |  | $ 0.01 |
Class Of Warrant Or Right. Aggregate Proceeds From Warrants Issued | $ 435,000 | $ 21,000,000 |  |  | $ 3,000,000 |  | $ 10,000,000 |  |
Common stock, shares authorized |  |  |  | 125,000,000 |  |  |  |  |
Dividends on common stock declared or paid |  |  |  | $ 0 |  |  |  |  |
Stock Issued During Period, Shares, New Issues |  |  |  | 900,000 |  |  |  |  |
Sale of stock, price per share (in usd per share) | $ 1.80 |  |  |  |  |  |  |  |
Class of warrant or right, warrants to purchase of common stock (in shares) |  |  |  | 766,666 |  |  |  |  |
Proceeds from issuance of common stock before underwriting discounts commissions and other expenses | $ 3,000,000 |  |  |  |  |  |  |  |
Funded |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |
Warrant exercise price (usd per share) | $ 8.69 |  |  |  | $ 1.79 |  | $ 4.97 |  |
Class B Warrants |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |
Issued |  | 5,416,667 |  |  |  |  |  |  |
Warrant exercise price (usd per share) |  | $ 15.00 |  |  |  |  |  |  |
Pre Funded Warrant |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |
Warrant exercise price (usd per share) |  | $ 11.999 |  |  |  |  |  |  |
Number of warrants for purchase of convertible preferred shares (in shares) |  |  |  |  |  |  |  |  | 1

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_ClassOfStockLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Exercise price per share or per unit of warrants or rights outstanding. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=123467817&loc=d3e21475-112644 + Details
Name: | us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of securities into which each warrant or right may be converted. For example, but not limited to, each warrant may be converted into two shares. + References No definition available. + Details
Name: | us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=123467817&loc=d3e21475-112644 + Details
Name: | us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of warrants or rights outstanding. + References No definition available. + Details
Name: | us-gaap_ClassOfWarrantOrRightOutstanding
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Face amount or stated value per share of common stock. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -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=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_CommonStockParOrStatedValuePerShare
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition The maximum number of common shares permitted to be issued by an entity's charter and bylaws. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -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=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_CommonStockSharesAuthorized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of paid and unpaid common stock dividends declared with the form of settlement in cash, stock and payment-in-kind (PIK). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -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=120397183&loc=d3e187085-122770 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 405 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6957935&loc=d3e64057-112817 + Details
Name: | us-gaap_DividendsCommonStock
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Per share amount received by subsidiary or equity investee for each share of common stock issued or sold in the stock transaction. + References No definition available. + Details
Name: | us-gaap_SaleOfStockPricePerShare
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of new stock issued during the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -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=120391452&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=123467817&loc=d3e21463-112644 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -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=120397183&loc=d3e187085-122770 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -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=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_StockIssuedDuringPeriodSharesNewIssues
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Class of Warrant or Right, Additional Exercise Price of Warrants or Rights + References No definition available. + Details
Name: | xfor_ClassOfWarrantOrRightAdditionalExercisePriceOfWarrantsOrRights
Namespace Prefix: | xfor_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Class Of Warrant Or Right. Aggregate Proceeds From Warrants Issued + References No definition available. + Details
Name: | xfor_ClassOfWarrantOrRightAggregateProceedsFromWarrantsIssued
Namespace Prefix: | xfor_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Class of warrant or right issued. + References No definition available. + Details
Name: | xfor_ClassOfWarrantOrRightIssued
Namespace Prefix: | xfor_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Class Of Warrant Or Right Warrants Expiration Period + References No definition available. + Details
Name: | xfor_ClassOfWarrantOrRightWarrantsExpirationPeriod
Namespace Prefix: | xfor_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Proceeds From Issuance Of Common Stock Before Underwriting Discounts Commissions And Other Expenses + References No definition available. + Details
Name: | xfor_ProceedsFromIssuanceOfCommonStockBeforeUnderwritingDiscountsCommissionsAndOtherExpenses
Namespace Prefix: | xfor_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | xfor_PrefundedWarrantsAxis=xfor_FundedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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