Nature Of Business And Summary Of Significant Accounting Policies (Narrative) (Details) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018 USD ($)	Dec. 31, 2019 USD ($) numberOfCustomers segment $ / shares customer shares	Dec. 31, 2018 USD ($) numberOfCustomers $ / shares shares	Dec. 31, 2017 USD ($) numberOfCustomers	Jan. 01, 2018 USD ($)	Jan. 01, 2017 USD ($)
Nature Of Business And Summary Of Significant Accounting Policies [Line Items]
Bank acceptances drafts		$ 16,484	$ 27,335
Bank acceptances, weighted-average maturity period		76 days
Long-lived assets		$ 617,960	$ 553,732
Common stock, shares authorized (in shares) | shares		175,000,000	175,000,000
Common stock, par value (in dollars per share) | $ / shares		$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares) | shares		5,000,000
Preferred stock, par value (in dollars per share) | $ / shares		$ 0.0001
Preferred stock, shares outstanding (in shares) | shares		0
Number of customers | numberOfCustomers		1	1	1
Number of largest customers | customer		5
Net sales by major customers, percentage		21.00%	26.00%	28.00%
Number of operating segments | segment		1
Deferred income tax assets		$ 31,395	$ 19,165	$ 26,976	$ 28,150
Recently adopted accounting standards					616	$ 4,223
Restricted Stock Units (RSUs)
Nature Of Business And Summary Of Significant Accounting Policies [Line Items]
Vesting period		4 years
Stock option
Nature Of Business And Summary Of Significant Accounting Policies [Line Items]
Vesting period		4 years
Retained Earnings
Nature Of Business And Summary Of Significant Accounting Policies [Line Items]
Recently adopted accounting standards					$ 606	2,145
Additional Paid In Capital
Nature Of Business And Summary Of Significant Accounting Policies [Line Items]
Recently adopted accounting standards						2,078
ASU 2018-02
Nature Of Business And Summary Of Significant Accounting Policies [Line Items]
Tax Cuts and Jobs Act of 2017, reclassification from AOCI to retained earnings	$ 10
Accounting Standards Update 2016-09, Excess Tax Benefit Component
Nature Of Business And Summary Of Significant Accounting Policies [Line Items]
Deferred income tax assets						3,464
Accounting Standards Update 2016-09, Excess Tax Benefit Component | Retained Earnings
Nature Of Business And Summary Of Significant Accounting Policies [Line Items]
Recently adopted accounting standards						3,464
Accounting Standards Update 2016-09, Forfeiture Rate Component
Nature Of Business And Summary Of Significant Accounting Policies [Line Items]
Deferred income tax assets						759
Accounting Standards Update 2016-09, Forfeiture Rate Component | Retained Earnings
Nature Of Business And Summary Of Significant Accounting Policies [Line Items]
Recently adopted accounting standards						(1,319)
Accounting Standards Update 2016-09, Forfeiture Rate Component | Additional Paid In Capital
Nature Of Business And Summary Of Significant Accounting Policies [Line Items]
Recently adopted accounting standards						$ 2,078
Minimum
Nature Of Business And Summary Of Significant Accounting Policies [Line Items]
Period for installation completion		1 year
Standard product warranty coverage period		1 year
Vesting period		1 year
Maximum
Nature Of Business And Summary Of Significant Accounting Policies [Line Items]
Period for installation completion		90 days
Standard product warranty coverage period		5 years
Vesting period		4 years
Intangible Assets | Minimum
Nature Of Business And Summary Of Significant Accounting Policies [Line Items]
Intangible asset, useful life		1 year
Intangible Assets | Maximum
Nature Of Business And Summary Of Significant Accounting Policies [Line Items]
Intangible asset, useful life		13 years
Demonstration Equipment
Nature Of Business And Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment useful life		3 years
Long-lived assets		$ 7,591	7,037
Amortization		$ 4,364	$ 3,870	$ 3,769
Sales
Nature Of Business And Summary Of Significant Accounting Policies [Line Items]
Percentage of net sales		9.00%	12.00%	13.00%
Accounts Receivable
Nature Of Business And Summary Of Significant Accounting Policies [Line Items]
Percentage of net sales		24.00%	25.00%