Summary of Significant Accounting Policies - Additional Information (Detail)		3 Months Ended				12 Months Ended
	Dec. 11, 2019 shares	Mar. 31, 2020 USD ($) Segment shares	Dec. 31, 2019 USD ($) shares	Sep. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($) shares	Dec. 10, 2019 shares
Accounting Policies [Line Items]
Reverse split, conversion ratio	0.0769
Common stock, shares outstanding (in shares) | shares	20,200,000	47,078,314	20,691,301			20,691,301	261,900,000
Accumulated deficit		$ 680,198,000	$ 663,600,000			$ 663,600,000
Working capital		26,900,000
Restricted cash		$ 900,000	1,000,000.0			1,000,000.0
Provision for doubtful accounts						1,600,000
Number of business segments | Segment		1
Goodwill impairment				$ 79,000,000.0		0
Period of service sale arrangement		5 years
Period of service sale arrangement at stated service price		4 years
Product warranty		1 year
Operating lease revenue		$ 100,000
Revenue, remaining performance obligation		3,500,000
Contract assets included in accounts receivable		200,000	200,000			200,000
Revenue recognized, included in deferred revenue		200,000			$ 300,000
Assets		84,230,000	74,779,000			74,779,000
Outside of U.S.
Accounting Policies [Line Items]
Assets		59,700,000	60,500,000			60,500,000
Stock Options
Accounting Policies [Line Items]
Share based compensation, expense recognized		$ 1,900,000			$ 3,000,000.0
Patents
Accounting Policies [Line Items]
Amortization period		10 years
Impairment of intangible assets		$ 0				$ 0
In-Process Research and Development
Accounting Policies [Line Items]
Impairment of intangible assets			$ 0	$ 7,900,000
Minimum
Accounting Policies [Line Items]
Amortization period		5 years
Minimum | Developed Technology
Accounting Policies [Line Items]
Amortization period		5 years
Maximum
Accounting Policies [Line Items]
Amortization period		10 years
Maximum | Developed Technology
Accounting Policies [Line Items]
Amortization period		7 years
Customer Concentration Risk | Accounts Receivable | Eight Customers
Accounting Policies [Line Items]
Concentration risk percentage		80.00%				85.00%
Customer Concentration Risk | Sales | Eleven Customers
Accounting Policies [Line Items]
Concentration risk percentage		80.00%
Customer Concentration Risk | Sales | Five Customer
Accounting Policies [Line Items]
Concentration risk percentage						81.00%
Geographic Concentration Risk | U.S.
Accounting Policies [Line Items]
Concentration risk percentage		27.00%			6.00%
Geographic Concentration Risk | Europe
Accounting Policies [Line Items]
Concentration risk percentage		48.00%			35.00%
Geographic Concentration Risk | Asia
Accounting Policies [Line Items]
Concentration risk percentage		25.00%			59.00%
Geographic Concentration Risk | Assets, Total | U.S.
Accounting Policies [Line Items]
Concentration risk percentage		29.00%				19.00%
Geographic Concentration Risk | Assets, Total | Outside of U.S.
Accounting Policies [Line Items]
Concentration risk percentage		71.00%				81.00%