Short-term and Long-term Debt - 2019 CTBC Credit Facility (Details)	1 Months Ended
	Jun. 30, 2019 USD ($)	Jan. 31, 2018 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2020 TWD ($)	Aug. 31, 2018 USD ($)	Jan. 31, 2018 TWD ($)
Short-term Debt [Line Items]
Short-term debt	$ 23,647,000		$ 23,704,000
Line of credit facility, amount outstanding	0		5,697,000
CTBC Bank | CTBC 2018 Facility
Short-term Debt [Line Items]
Credit facility, maximum borrowing capacity		$ 50,000,000.0			$ 40,000,000.0
Secured debt | Term loan | CTBC Credit Facility
Short-term Debt [Line Items]
Short-term debt	$ 22,531,000		23,704,000
Secured debt | CTBC Bank | Term loan | CTBC Credit Facility
Short-term Debt [Line Items]
Credit facility, term	12 months	12 months
Credit facility, maximum borrowing capacity		$ 23,600,000	22,500,000	$ 700,000,000.0		$ 700,000,000.0
Line of credit facility, amount outstanding	$ 0		0
Customs Bond | CTBC Bank | Term loan | CTBC Credit Facility, 12 Month, Up To 0.50% Interest
Short-term Debt [Line Items]
Credit facility, term	12 months	12 months
Credit facility, maximum borrowing capacity		$ 3,400,000	$ 3,200,000	$ 100,000,000.0		$ 100,000,000.0
Interest rate, stated percentage		0.50%	0.50%	0.50%		0.50%
Customs Bond | CTBC Bank | Term loan | CTBC Credit Facility, 12 Month, Up To 0.25% Interest
Short-term Debt [Line Items]
Credit facility, term		12 months
Credit facility, maximum borrowing capacity		$ 50,500,000				$ 1,500,000,000.0
Customs Bond | CTBC Bank | Term loan | CTBC Credit Facility, 180 Day, Up To 100% Of Eligible Accounts Receivable, Between 0.30% And 0.50% Percent Interest
Short-term Debt [Line Items]
Credit facility, term	180 days
Credit facility, maximum borrowing capacity			$ 48,200,000	$ 1,500,000,000.0
Percent of eligible accounts receivable			100.00%	100.00%
Customs Bond | CTBC Bank | Line of credit | CTBC Credit Facility
Short-term Debt [Line Items]
Credit facility, maximum borrowing capacity			$ 50,000,000.0
Customs Bond | CTBC Bank | Line of credit | CTBC Credit Facility, 12 Month, Up To 100% Of Eligible Accounts Receivable, Between 0.30% And 0.50% Interest
Short-term Debt [Line Items]
Credit facility, term	12 months
Credit facility, maximum borrowing capacity			$ 50,000,000.0
Percent of eligible accounts receivable			100.00%	100.00%
Revolving Credit Facility | Line of credit | CTBC Credit Facility
Short-term Debt [Line Items]
Credit facility, remaining borrowing capacity			$ 26,300,000
Collateral amount			$ 25,400,000
CTBC's Established NTD Interest Rate | Secured debt | CTBC Bank | Term loan | CTBC Credit Facility
Short-term Debt [Line Items]
Credit facility, basis spread on variable rate (as a percent)	0.25%	0.25%
CTBC's Established NTD Interest Rate | Customs Bond | CTBC Bank | Term loan | CTBC Credit Facility, 12 Month, Up To 0.25% Interest
Short-term Debt [Line Items]
Credit facility, basis spread on variable rate (as a percent)		0.25%
Minimum | CTBC's Established NTD Interest Rate | Customs Bond | CTBC Bank | Term loan | CTBC Credit Facility, 180 Day, Up To 100% Of Eligible Accounts Receivable, Between 0.30% And 0.50% Percent Interest
Short-term Debt [Line Items]
Credit facility, basis spread on variable rate (as a percent)	0.30%
Minimum | CTBC's Established USD Interest Rate | Customs Bond | CTBC Bank | Line of credit | CTBC Credit Facility, 12 Month, Up To 100% Of Eligible Accounts Receivable, Between 0.30% And 0.50% Interest
Short-term Debt [Line Items]
Credit facility, basis spread on variable rate (as a percent)	0.30%
Maximum | CTBC Bank
Short-term Debt [Line Items]
Interest rate (as a percent)	0.93%		0.45%	0.45%
Maximum | CTBC's Established NTD Interest Rate | Customs Bond | CTBC Bank | Term loan | CTBC Credit Facility, 180 Day, Up To 100% Of Eligible Accounts Receivable, Between 0.30% And 0.50% Percent Interest
Short-term Debt [Line Items]
Credit facility, basis spread on variable rate (as a percent)	0.50%
Maximum | CTBC's Established USD Interest Rate | Customs Bond | CTBC Bank | Line of credit | CTBC Credit Facility, 12 Month, Up To 100% Of Eligible Accounts Receivable, Between 0.30% And 0.50% Interest
Short-term Debt [Line Items]
Credit facility, basis spread on variable rate (as a percent)	0.50%