Summary of Significant Accounting Policies - Additional Information (Detail)	1 Months Ended	12 Months Ended
	Jun. 30, 2016	Dec. 31, 2018 USD ($) Subsidiary Business Customer	Dec. 31, 2017 USD ($) Customer	Dec. 31, 2016 USD ($) Customer
Summary Of Significant Accounting Policies [Line Items]
Number of wholly owned subsidiaries | Subsidiary		4
Number of business activities | Business		1
Net unrealized foreign currency transaction gains (losses)		$ (600,000)	$ 800,000	$ (1,600,000)
Realized foreign currency transaction gains (losses)		(400,000)	500,000	700,000
Cash held in foreign banks		4,100,000	4,500,000
Money market funds		15,600,000	30,300,000
Restricted cash		606,000	806,000
Write down of inventory		$ 2,005,000	3,984,000	4,056,000
Standard product warranty, description		Limited one- to five-year warranty
Impairment charges		$ 0
Interest or penalties recognized		$ 0	0	$ 0
Employee stock purchase plan offering period		6 months
RSU's [Member]
Summary Of Significant Accounting Policies [Line Items]
Vesting term		4 years
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of property and equipment		3 years
Minimum [Member] | ASU No. 2016-02 [Member]
Summary Of Significant Accounting Policies [Line Items]
Right-of-use assets		$ 24,300,000
Lease liabilities		$ 25,700,000
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of property and equipment		5 years
Maximum [Member] | ASU No. 2016-02 [Member]
Summary Of Significant Accounting Policies [Line Items]
Right-of-use assets		$ 25,300,000
Lease liabilities		26,700,000
Certificate of Deposit [Member]
Summary Of Significant Accounting Policies [Line Items]
Restricted cash		$ 600,000	600,000
Collateralizing Payment Charges Related to Credit Cards [Member]
Summary Of Significant Accounting Policies [Line Items]
Restricted cash			$ 200,000
Customer Concentration Risk [Member] | Revenue [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage		10.00%	10.00%	10.00%
Number of customers accounted 10% or more concentration risk | Customer		0	0	0
Credit Concentration Risk [Member] | Accounts Receivable [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage		10.00%	10.00%
Number of customers accounted 10% or more concentration risk | Customer		0	0
1.75% Convertible Senior Notes due 2021 [Member]
Summary Of Significant Accounting Policies [Line Items]
Debt instrument due year	2021	2021