Property and Equipment - Property and Equipment (Detail) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	$ 16,647,000us-gaap_PropertyPlantAndEquipmentGross	$ 11,807,000us-gaap_PropertyPlantAndEquipmentGross
Less: Accumulated depreciation and amortization	(10,281,000)	(8,742,000)
Property and Equipment, net	6,366,000us-gaap_PropertyPlantAndEquipmentNet	3,065,000us-gaap_PropertyPlantAndEquipmentNet
Manufacturing Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Useful Life	5 years
Property and Equipment, gross	3,654,000	3,333,000
Lease and Loaner Instruments [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	2,629,000	0
Less: Accumulated depreciation and amortization	(128,000)	0
Lease and Loaner Instruments [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Useful Life	1 year
Lease and Loaner Instruments [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Useful Life	5 years
Prototype Instruments [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Useful Life	2 years
Property and Equipment, gross	2,157,000	1,893,000
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Useful Life	3 years
Property and Equipment, gross	1,430,000	1,325,000
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Useful Life	5 years
Property and Equipment, gross	831,000	543,000
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Useful Life	Life of the related assets or the term of the lease, whichever is less
Property and Equipment, gross	4,888,000	4,713,000
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	$ 1,058,000	$ 0

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

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.14)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 14

-Article 5

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- Definition

Describes the periods of time over which an entity anticipates to receive utility from its property, plant and equipment (that is, the periods of time over which an entity allocates the initial cost of its property, plant and equipment).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6367646&loc=d3e18780-107790

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 35

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6539997&loc=d3e1205-110223

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- Definition

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

-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

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- Definition

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

-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

-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 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 13

-Subparagraph a

-Article 5

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 8

-Article 7

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- Definition

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

+ Details

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