Property and Equipment - Property and Equipment (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	$ 21,849,000	$ 16,647,000
Less: Accumulated depreciation and amortization	(12,435,000)	(10,281,000)
Property and Equipment, net	$ 9,414,000	6,366,000
Manufacturing Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Useful Life	5 years
Property and Equipment, gross	$ 4,543,000	3,654,000
Lease and Loaner Instruments [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	3,318,000	2,629,000
Less: Accumulated depreciation and amortization	$ (867,000)	(128,000)
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	$ 2,956,000	2,157,000
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Useful Life	3 years
Property and Equipment, gross	$ 1,847,000	1,430,000
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Useful Life	5 years
Property and Equipment, gross	$ 1,390,000	831,000
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 shorter
Property and Equipment, gross	$ 5,874,000	4,888,000
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	$ 1,921,000	$ 1,058,000