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Debt - Narrative (Details)		1 Months Ended										12 Months Ended
Debt - Narrative (Details)	Feb. 25, 2015 JPY (¥)	Jan. 31, 2019 USD ($)	Aug. 31, 2018 USD ($)	Feb. 28, 2018 USD ($)	Jan. 31, 2018 USD ($)	Jan. 31, 2018 JPY (¥)	Dec. 31, 2017 USD ($)	Nov. 30, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jul. 31, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($) debt_instrument	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($) letter_of_credit	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 JPY (¥)	Jan. 31, 2018 JPY (¥)	Dec. 31, 2017 CNY (¥)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 JPY (¥)	Feb. 25, 2015 USD ($)	Feb. 25, 2015 JPY (¥)
Debt Instrument [Line Items]
Number of letters of credit issued \| letter_of_credit														3
Repayment of notes payable												$ 3,732,000	$ 11,639,000	$ 18,007,000
Comerica \| Revolving Credit Facility
Debt Instrument [Line Items]
Current borrowing capacity														$ 30,000,000
Mitsubishi Bank
Debt Instrument [Line Items]
Short-term line of credit facility \| ¥																¥ 616,800,000
Senior Secured Revolving Credit Facility, expires April 2017 \| Federal Funds Effective Rate \| Comerica
Debt Instrument [Line Items]
Debt instrument, basis spread									1.00%
Senior Secured Revolving Credit Facility, expires April 2017 \| Daily Adjusting LIBOR Rate \| Comerica
Debt Instrument [Line Items]
Debt instrument, basis spread									1.00%
Senior Secured Revolving Credit Facility, expires April 2017 \| Libor Plus Rate \| Comerica
Debt Instrument [Line Items]
Debt instrument, basis spread									2.75%
Senior Secured Revolving Credit Facility, expires April 2017 \| Credit Facility Base Rate \| Comerica
Debt Instrument [Line Items]
Debt instrument, basis spread									1.75%
Wells Fargo Credit Facility \| Line of Credit
Debt Instrument [Line Items]
Line of credit maximum borrowing capacity									$ 50,000,000.0
Short-term line of credit facility									$ 30,000,000
Outstanding balance of line of credit facilities												$ 36,000,000
Cash balance available for borrowing									100.00%
Cash balance max borrowing									$ 15,000,000.0
Line of credit facility, increase (decrease)									25,000,000
Repayment of notes payable									$ 20,000,000
Line of credit facility, collateral									20.0
Unused borrowing capacity									$ 5,000,000
Interest rate							3.29%					4.41%	3.29%		4.41%	4.41%		3.29%
Line of credit remaining borrowing capacity												$ 14,000,000
Required amount to be maintained as unused borrowing capacity												5,000,000
Wells Fargo Credit Facility \| Prime Rate \| Line of Credit
Debt Instrument [Line Items]
Commitment fee									0.25%
Term Loan A \| Mitsubishi Bank
Debt Instrument [Line Items]
Debt, aggregate principal amount																					$ 4,400,000	¥ 500,000,000
Term Loan A \| Tokyo Interbank Offered Rate (TIBOR) \| Mitsubishi Bank
Debt Instrument [Line Items]
Debt instrument, basis spread	1.40%
Term Loan B \| Mitsubishi Bank
Debt Instrument [Line Items]
Debt, aggregate principal amount																					9,100,000	1,000,000,000
Debt, periodic principal payments \| ¥	¥ 8,333,000
Debt, lump sum payment on the maturity date \| ¥	¥ 8,373,000
Debt issuance costs																					$ 400,000	¥ 40,500,000
Term Loan B \| Tokyo Interbank Offered Rate (TIBOR) \| Mitsubishi Bank
Debt Instrument [Line Items]
Debt instrument, basis spread	1.40%
Mitsubishi Bank Term Loan A \| Notes Payable to Banks
Debt Instrument [Line Items]
Short-term line of credit facility												5,600,000
Repayments of lines of credit					$ 4,400,000	¥ 500,000,000
Mitsubishi Bank Loans \| Notes Payable to Banks
Debt Instrument [Line Items]
Unamortized debt issuance costs												600,000				¥ 66,200,000
Mitsubishi Bank Loan 2017 \| Notes Payable to Banks
Debt Instrument [Line Items]
Short-term line of credit facility											$ 6,300,000									¥ 690,000,000
Debt, aggregate principal amount											$ 6,300,000									¥ 690,000,000
Debt instrument term					72 months	72 months
Mitsubishi Bank Loan 2017 \| Tokyo Interbank Offered Rate (TIBOR) \| Notes Payable to Banks
Debt Instrument [Line Items]
Debt instrument, basis spread											1.00%
Term Loan C \| Mitsubishi Bank and The Tamanashi Chou Ban, Ltd.
Debt Instrument [Line Items]
Line of credit maximum borrowing capacity					$ 7,700,000												¥ 850,000,000
Debt instrument term					82 months	82 months
Term Loan C \| Tokyo Interbank Offered Rate (TIBOR) \| Mitsubishi Bank and The Tamanashi Chou Ban, Ltd.
Debt Instrument [Line Items]
Debt instrument, basis spread					1.00%	1.00%
Notes Payable \| Second Line Of Credit, Expires July 2019 \| Subsidiary in China
Debt Instrument [Line Items]
Short-term line of credit facility												4,400,000			¥ 30,000,000
Bankers Acceptance
Debt Instrument [Line Items]
Restricted cash and investments, current							$ 500,000					$ 2,600,000	$ 500,000
Bankers Acceptance \| Subsidiary in China
Debt Instrument [Line Items]
Outstanding balance of line of credit facilities							$ 1,600,000						$ 1,600,000
Bankers Acceptance \| Second Line Of Credit, Expires July 2019 \| Subsidiary in China
Debt Instrument [Line Items]
Percentage of compensating balance requirement for bank acceptance drafts												50.00%
Short-term line of credit facility												$ 8,700,000			¥ 60,000,000
Bankers Acceptance \| First Credit Facility Expires July 2019
Debt Instrument [Line Items]
Percentage of compensating balance requirement for bank acceptance drafts														30.00%
Line of Credit \| Amended Comerica Bank Credit Facility
Debt Instrument [Line Items]
Current borrowing capacity																			$ 17,000,000.0
Line of credit facility, maximum indebtedness under debt covenant																			$ 20,000,000.0
Notes Payable to Banks \| Note payable to China CITIC Bank
Debt Instrument [Line Items]
Borrowing on line of credit				$ 17,000,000						$ 17,000,000
Debt instrument, basis spread										2.55%
Stated interest rate				4.70%
Repayments of lines of credit			$ 17,000,000
Interest rate							4.00%					0.00%	4.00%		0.00%	0.00%		4.00%
China \| CITIC Bank \| Bank Acceptance Drafts
Debt Instrument [Line Items]
Line of credit maximum borrowing capacity							$ 56,800,000						$ 56,800,000					¥ 390,600,000
Percentage of compensating balance requirement for bank acceptance drafts							36.00%
China \| CITIC Bank \| Line of Credit
Debt Instrument [Line Items]
Line of credit maximum borrowing capacity							$ 36,400,000						$ 36,400,000					¥ 250,000,000
China \| First Credit Facility Expires June 2016
Debt Instrument [Line Items]
Percentage of compensating balance requirement for bank acceptance drafts												50.00%
China \| Notes Payable
Debt Instrument [Line Items]
Number of credit facilities \| debt_instrument												2
China \| Notes Payable \| First Credit Facility Expires June 2016
Debt Instrument [Line Items]
Short-term line of credit facility												$ 17,400,000			¥ 120,000,000
Borrowing on line of credit								$ 17,000,000
China \| Bankers Acceptance
Debt Instrument [Line Items]
Outstanding balance of line of credit facilities												4,800,000
China \| Bankers Acceptance \| First Credit Facility Expires June 2016
Debt Instrument [Line Items]
Line of credit maximum borrowing capacity												$ 34,900,000			¥ 240,000,000
Debt instrument, basis spread								4.10%
China \| Notes Payable to Banks \| Note payable to China CITIC Bank
Debt Instrument [Line Items]
Repayments of lines of credit					$ 17,000,000
Minimum \| Mitsubishi Bank
Debt Instrument [Line Items]
Interest rate							1.05%					1.05%	1.05%		1.05%	1.05%		1.05%
Minimum \| Wells Fargo Credit Facility \| Line of Credit
Debt Instrument [Line Items]
Revolver accounts receivable									80.00%
Minimum \| Wells Fargo Credit Facility \| Credit Facility Base Rate \| Line of Credit
Debt Instrument [Line Items]
Debt instrument, basis spread									1.50%
Minimum \| Wells Fargo Credit Facility \| Prime Rate \| Line of Credit
Debt Instrument [Line Items]
Debt instrument, basis spread									0.50%
Maximum \| Mitsubishi Bank
Debt Instrument [Line Items]
Interest rate							1.45%					1.45%	1.45%		1.45%	1.45%		1.45%
Maximum \| Wells Fargo Credit Facility \| Line of Credit
Debt Instrument [Line Items]
Revolver accounts receivable									85.00%
Maximum \| Wells Fargo Credit Facility \| Credit Facility Base Rate \| Line of Credit
Debt Instrument [Line Items]
Debt instrument, basis spread									1.75%
Maximum \| Wells Fargo Credit Facility \| Prime Rate \| Line of Credit
Debt Instrument [Line Items]
Debt instrument, basis spread									0.75%
Financial Standby Letter of Credit
Debt Instrument [Line Items]
Outstanding letters of credit														$ 1,600,000
Subsequent Event \| Wells Fargo Credit Facility \| Line of Credit
Debt Instrument [Line Items]
Repayments of lines of credit		$ 5,000,000