Supplemental Balance Sheet Information - Property and Equipment - (Details) - USD ($)	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015
Property and Equipment
Property and equipment, gross	$ 20,655,000	$ 15,462,000
Accumulated depreciation and amortization	(7,066,000)	(4,807,000)
Property and equipment, net	13,589,000	10,655,000
Office and computer equipment
Property and Equipment
Property and equipment, gross	$ 409,000	395,000
Estimated useful lives (Years)	3 years
Software
Property and Equipment
Property and equipment, gross	$ 708,000	632,000
Estimated useful lives (Years)	3 years
Laboratory equipment
Property and Equipment
Property and equipment, gross	$ 4,516,000	4,112,000
Estimated useful lives (Years)	5 years
Furniture
Property and Equipment
Property and equipment, gross	$ 200,000	187,000
Furniture \| Minimum
Property and Equipment
Estimated useful lives (Years)	5 years
Furniture \| Maximum
Property and Equipment
Estimated useful lives (Years)	7 years
Manufacturing equipment
Property and Equipment
Property and equipment, gross	$ 897,000	577,000
Estimated useful lives (Years)	5 years
Manufacturing tooling and molds
Property and Equipment
Property and equipment, gross	$ 154,000	71,000
Estimated useful lives (Years)	6 months
T2-owned instruments and components
Property and Equipment
Property and equipment, gross	$ 9,119,000	4,960,000
Estimated useful lives (Years)	5 years
Leasehold improvements
Property and Equipment
Property and equipment, gross	$ 3,353,000	3,332,000
Construction in progress
Property and Equipment
Property and equipment, gross	1,299,000	1,196,000
T2 Owned Instruments in Service
Property and Equipment
Property and equipment, gross	$ 5,700,000
Estimated useful lives (Years)	5 years
Depreciation expense recorded as a component of cost of product revenue	$ 599,000	$ 105,000

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section S99
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The expense recognized in the current period that allocates the cost of a tangible asset over the asset's useful life. This element applies only to an asset used in the production of goods sold.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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+ 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 210.5-02.13)
-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
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-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 13
-Subparagraph a
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
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