Contractual deferred interest rate during interest only payments for funds borrowed, under the debt agreement.

No definition available.

Name:	ttoo_DebtInstrumentDeferredInterestRateInterestOnlyPayment
Namespace Prefix:	ttoo_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Additional interest rate on all outstanding obligations during the occurrence and continuance of an event of default.

+ References

No definition available.

+ Details

Name:	ttoo_DebtInstrumentEventOfDefaultAdditionalInterestRate
Namespace Prefix:	ttoo_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Extended period of time between issuance and maturity of debt instrument of interest only payments, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	ttoo_DebtInstrumentExtendedTermInterestOnlyPayments
Namespace Prefix:	ttoo_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Final fee as a percentage of the amount of principal outstanding upon repayment.

+ References

No definition available.

+ Details

Name:	ttoo_DebtInstrumentFinalPaymentFeePercentage
Namespace Prefix:	ttoo_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Prepayment fee period of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	ttoo_DebtInstrumentPrepaymentFeeTerm
Namespace Prefix:	ttoo_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Period of time between issuance and maturity of debt instrument of interest only payments, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	ttoo_DebtInstrumentTermofInterestOnlyPayments
Namespace Prefix:	ttoo_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The contingent increase above the maximum borrowing capacity under the credit facility, if any one or more of the existing banks or new banks agree to provide such increased commitment amount.

+ References

No definition available.

+ Details

Name:	ttoo_LineOfCreditFacilityContingentIncreaseAdditionalBorrowingCapacity
Namespace Prefix:	ttoo_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Number of Warrants Issued

+ References

No definition available.

+ Details

Name:	ttoo_NumberofWarrantsIssued
Namespace Prefix:	ttoo_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The portion of proceeds used for the repayment of debt.

+ References

No definition available.

+ Details

Name:	ttoo_PortionofProceedsUsedForDebtRepayment
Namespace Prefix:	ttoo_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Exercise price per share or per unit of warrants or rights outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i)(4))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

Name:	us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- 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/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i)(2))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

Name:	us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ 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 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- 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

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash inflow from additional borrowings, net of cash paid to third parties in connection with debt origination.

+ References

No definition available.

+ Details

Name:	us-gaap_ProceedsFromDebtNetOfIssuanceCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer.

+ 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 (b)
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3255-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Financing Activities
-URI http://asc.fasb.org/extlink&oid=6513228

+ Details

Name:	us-gaap_ProceedsFromIssuanceOfLongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash outflow for a borrowing supported by a written promise to pay an obligation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Financing Activities
-URI http://asc.fasb.org/extlink&oid=6513228

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3291-108585

+ Details

Name:	us-gaap_RepaymentsOfNotesPayable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Fair value portion of warrants not settleable in cash classified as equity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

+ Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=ttoo_LoanAndSecurityAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ttoo_PromissoryNoteMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=ttoo_CRGServicingLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ttoo_TermLoanAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ttoo_DebtCovenantTermsAxis=ttoo_PriortoApprovalMilestoneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ttoo_DebtCovenantTermsAxis=ttoo_FollowingApprovalMilestoneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=us-gaap_CommonStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Notes Payable - Term Loan Agreement (Details) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended
	Dec. 31, 2016 USD ($) warrant $ / shares shares	Mar. 31, 2017 USD ($)	Mar. 31, 2016 USD ($)
Debt Instrument
Repayments of note payable		$ 299	$ 80
Loan And Security Agreement
Debt Instrument
Repayments of note payable	$ 27,500
Promissory Note
Debt Instrument
Repayments of note payable	500
CRG Servicing LLC \| Term Loan Agreement
Debt Instrument
Proceeds from issuance of long-term debt	40,000
Line of credit, additional borrowing capacity	$ 10,000
Debt term (in years)	6 years
Debt instrument, term of interest-only payments (in years)	3 years
Debt instrument, extended term interest only payments (in years)	4 years
Final fee as a percentage of the principal outstanding (as a percent)	8.00%
Debt instrument, prepayment fee term (in years)	5 years
Additional interest rate, event of default (as a percent)	4.00%
Proceeds from issuance of note payable, net	$ 39,200
Portion of proceeds used for debt repayment	$ 28,000
Number of warrants \| warrant	4
Prior to Approval Milestone \| CRG Servicing LLC \| Term Loan Agreement
Debt Instrument
Annual fixed rate (as a percent)	12.50%
Deferred interest rate (as a percent)	4.00%
Following Approval Milestone \| CRG Servicing LLC \| Term Loan Agreement
Debt Instrument
Annual fixed rate (as a percent)	11.50%
Deferred interest rate (as a percent)	3.50%
Common stock
Debt Instrument
Number of warrants \| warrant	4
Number of shares issuable for warrants outstanding (in shares) \| shares	528,958
Exercise price of warrants (in dollars per share) \| $ / shares	$ 8.06
Fair market value of warrants	$ 1,800